What is “collective immunity” to coronavirus?
- Teller Report Teller Report Now you can see non-English news... What is “collective immunity” to coronavirus?
2020-03-24T16:10:24.353Z While some countries have adopted the strategy of collective immunity, before changing their mind, focus on this method rather criticized by scientists Two British in London, wearing masks.
For ten days, while France had taken containment measures, Boris Johnson was banking on collective immunity.
But the UK has changed its strategy.
- Matt Dunham / AP / SIPA The United Kingdom had for a time chosen to bet on "collective immunity" to avoid confinement and blockage of the country.
But for the past few days, these two countries seem to have changed their minds.
When you reach a reproduction rate of 1, the epidemic no longer spreads. "
This is why some countries have chosen not to confine populations, hoping that a rapid spread of the virus, once it has affected 60% of citizens, would provoke protective collective immunity in the long term.
Find our file To illustrate this concept, Mircea T. Sofonea, lecturer in epidemiology and evolution of infectious diseases at the University of Montpellier, takes an analogy: "An epidemic can be represented as a forest fire that spreads quickly.
The first models were published in the 1930s.
Working on Spanish flu at the start of the 20th century, mathematicians discovered that an epidemic does not die "for lack of combatants" - a situation in which the infectious agent would eventually disappear with the patients he kills - but by acquiring "gregarious immunity", explains Antoine Flahault, specialist in public health and epidemiology at AFP.
But this concept is mainly used to fight epidemics when you have a vaccine, to determine the rate of vaccine coverage necessary, to be sure that smallpox or measles will disappear, for example.
Little by little, some countries that wanted to build on this approach have revised their copies.
At first, the British Boris Johnson popularized the term "collective immunity".
While France imposed confinement on the entire population (with some exceptions), our British neighbors were invited to wash their hands.
If the Prime Minister, Mark Rutte, no longer excludes a total containment of the population, he hopes "that it will not be necessary".
Mark Rutte had declared last week wanting to favor the development of a collective immunity in the Netherlands of which, he had warned, most of the inhabitants would be contaminated.
The only European country to go it alone, Sweden has not followed the path of containment.
Another concern: there are still a lot of questions about this Covid-19.
And one of the questions is about long-term immunity to this coronavirus: basically, can you get this disease twice?
"For Sras, a coronavirus close to Covid-19, studies have shown that antibodies can drop after two years," says Mircea T. Sofonea.
This means that for this close virus, immunity is not guaranteed for life.
Please note that this cannot be transposed to Covid-19, which has only been discovered since December.
No one can tell you if people who have been infected will have a persistent immune memory within a year.
"Nothing says that group immunity is sufficient if the pandemic continues in other countries, that it circulates there quietly," continues the expert.
And come back in a few months with mutations such that our immunity would not recognize it.

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Collective immunity will not save us from the coronavirus pandemic – National Collective immunity will not save us from the coronavirus pandemic – National July 12, 2020 262 Share Throughout the months of March and April, Spain was one of the countries hardest hit by the coronavirus.
Related news Since then, the epidemic has slowed, but the country has so far registered about 253,000 cases and 28,000 deaths – more than twice as many cases and three times more deaths than Canada, according to data from the University.
Furthermore, it seemed that these antibodies had disappeared within a few months.
The story continues under advertising Experts say this is bad news for proponents of natural “collective immunity” – the idea that if enough people catch the virus, the population will ultimately be protected from future epidemics.
Read more: Spain hits coronavirus record as Europe rushes to build hospitals “We are a long way from reaching a level of immunity that would protect Spain from future epidemics,” said Ashleigh Tuite, infectious disease epidemiologist at the University of Toronto.
And even in the hardest hit places, they are still vulnerable to waves of subsequent infections.
“ About “collective immunity” Usually, according to Tuite, the term “collective immunity” is used to describe immunization coverage.
As in, you need around 95 percent of people to be vaccinated against measles so that this group is protected from future measles epidemics.
Read more: Measles outbreak – what parents need to know about collective immunity You can also get immunity from a disease without being vaccinated, but it takes a lot of people to get it.
The story continues under advertising Dr. Nelson Lee, a professor at the University of Alberta who studies infectious diseases, says that for influenza, you start to get a little protection from the population at around 40% immunity, but for real protection, it must be closer to 70% of immunized people.
1:56 Coronavirus epidemic: collective immunity is not a concept that should be supported, “says Tam Coronavirus epidemic: collective immunity is not a concept that should be supported, “says Tam “In fact, we do not know what level of collective immunity is required for COVID-19,” he said, adding, “There would be a huge price to pay” to reach a level similar to that of influenza.
[ Sign up for our Health IQ newsletter for the latest coronavirus updates ] “If you infect a lot of people in the community, there will be a lot of serious illness and death.” Even in Sweden, where infection rates were higher because there were few restrictions at the start, there has been little demonstrated immunity, he said, despite a very high death toll.
The story continues under advertising Read more: What is collective immunity and what does it mean for COVID-19?
It’s also unclear exactly how the presence of antibodies, which most tests are looking for, translates into immunity against a new infection, Tuite said.
“We don’t really know for sure,” she said.
“Because it is a new virus, we can examine the immune response and examine the antibodies and try to deduce how many people have been infected.” But we don’t really know how long-lasting this immunity is.
” “I think a huge assumption with any sort of strategy based on collective immunity is that immunity is long-term, which we don’t fully know at this point.” End the pandemic The bottom line, Tuite thinks, is that it would be a bad idea to let the virus run its course until enough people have been infected to theoretically achieve collective immunity.
“Collective immunity may be an outcome that occurs during the pandemic, but it should not be a strategy.” The infection curve would not stop only when 70% of people were infected either, she said – cases would tend to decline slowly over time.
The story continues under advertising Read more: Does letting children contract the coronavirus help strengthen immunity in Quebec society?
And while the idea of ​​letting the virus run its course was launched in the UK at the start of the pandemic, and countries like Sweden have chosen not to close at the same level as their neighbors, Tuite said.
it was not aware of any country actively pursuing collective immunity as a strategy at this time.
1:47 Coronavirus outbreak: evidence shows that collective immunity has not been reached Coronavirus outbreak: evidence shows that collective immunity has not been reached However, parts of the United States could test this by default, she said.
“There is a strategy of letting the virus spread without really concentrating or making efforts to control it.
The uncontrolled spread is sort of saying de facto, “Well, we will leave that spread until we have immunity in the population.” Read more: Legault pushes collective immunity before the gradual reopening of schools The story continues under advertising With an uncontrolled spread, we can expect a “substantial proportion [of people] would develop a serious illness, and some of them will have to be hospitalized and die, “said Lee.
There are also reports of people who have lasting damage or long-term symptoms as a result of COVID-19.
For all these reasons, a commentary published alongside this week’s study on Spain called a collective immunity strategy both “highly unethical” and “unworkable”.
It would be far better to end the pandemic with a vaccine, Lee thinks.

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Collective immunity: why some believe it could end the coronavirus pandemic Collective immunity: why some believe it could end the coronavirus pandemic April 23, 2020 236 Share As the coronavirus pandemic spreads worldwide, doctors, scientists and heads of government have said that once collective immunity is achieved, the spread of the virus will be less threatening.
Collective immunity is reached when the majority of a given population – 70 to 90% – becomes immune to an infectious disease, either because they become infected and have recovered, or through vaccination.
When this happens, the disease is less likely to spread to people who are not immune, because there simply are not enough infectious carriers to reach them.
There are only two ways to get there: generalized vaccination, which for Covid-19 is still several months away, or generalized infections which lead to immunity.
Most doctors and experts agree that allowing Covid-19 to plow people could help achieve collective immunity faster, but it would also overwhelm hospitals.
“The advantage of expanding the number of cases is that we will not exceed the capacity of hospitals to care for particularly sick people,” Dr. H. Cody Meissner, chief of pediatric infectious diseases at Tufts University Medical, told CNN.
Then there is the problem that we don’t really know how immunity works with this virus.
World Health Organization (WHO) infectious disease epidemiologist Dr. Maria Van Kerkhove said that it is unknown whether people who have been exposed to the virus are fully immune to it and, if so, , for how long.
The WHO has “seen preliminary results, preliminary studies, pre-published results, in which some people will develop an immune response,” said Van Kerkhove.
“We don’t know if that actually confers immunity, which means they are fully protected.
“ A vaccine is a better answer, she added.
” And while young people are much less likely to die from Covid-19, they can still fall ill enough to require hospitalization.
Although catching Covid-19 once makes people immune to future infection, the United States has not had enough cases to come close to generalized immunity.
“The level of people who have been infected, I don’t expect it to reach this level to give what we call immune protection for the herd,” said Dr. Anthony Fauci, director of the National Institute allergies and infectious diseases.
“What that would mean would protect those who were exposed, but at the community level, there would not have been enough infections to really have enough immune protection,” said Fauci.
As a vaccine has not yet been created for the new coronavirus, some have argued that nations should give up closures altogether and try to achieve collective immunity by keeping the vulnerable inside while allowing others to live their normal lives – and be infected.
Prime Minister Boris Johnson appeared to support a similar belief in March when he suspended the ban on large rallies and the closure of schools.
Restaurants, schools and playgrounds in the Scandinavian country are open.
Swedish Foreign Minister Ann Linde has said that she does not follow the theory of collective immunity, but rather relies on its citizens to make them willingly responsible for preventing the spread of the coronavirus.
But Swedish state epidemiologist Anders Tegnell said that collective immunity could be reached in the national capital, Stockholm, in a few weeks.
“In most parts of Sweden, around Stockholm, we have reached a plateau (in new cases) and we are already seeing the effects of collective immunity and in a few weeks we will see even more,” Tegnell said.
said in an interview with CNBC.
This is why so many people ask for antibody tests.
With the touch of a finger, tests to find out if you have contracted the coronavirus can help public health officials determine which part of the population has been infected and, in theory anyway, has least some immunity to the virus, said Caroline Buckee, associate professor of epidemiology at Harvard TH’s Chan School of Public Health.
A city in California has already started testing antibodies to its residents.

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Getty Images/Science Photo Libra More On: Antibodies against the coronavirus declined rapidly among hundreds of thousands of people involved in a British study, suggesting that immunity after infection may not last long, according to reports.
Scientists at Imperial College London tracked in the British population after the first wave of infections in March and April, Reuters reported.
Antibody prevalence fell by a quarter, from 6 percent of the population around the end of June to just 4.4 percent in September – raising the prospect of decreasing immunity ahead of a second wave of infections, according to the outlet.
Imperial’s study — based on a survey of 365,000 randomly selected adults who received finger-prick tests — was released as a pre-print paper, and has not yet been peer-reviewed.
“We observe a significant decline in the proportion of the population with detectable antibodies over three rounds of national surveillance, using a self-administered lateral flow test, 12, 18 and 24 weeks after the first peak of infections in England,” the team wrote, .
“This is consistent with evidence that immunity to seasonal coronaviruses declines over 6 to 12 months after infection and emerging data on SARS-CoV-2 that also detected a decrease over time in antibody levels in individuals followed in longitudinal studies,” it added.
For health care workers, the IgG antibody rates stayed about the same, according to the study, which was published Monday by Imperial College London and market research company Ipsos MORI.
Getty Images “We can see the antibodies and we can see them declining and we know that antibodies on their own are quite protective,” Wendy Barclay, head of the Department of Infectious Disease at Imperial College London, said at a press conference.
“On the balance of evidence I would say, with what we know for other coronaviruses, it would look as if immunity declines away at the same rate as antibodies decline away, and that this is an indication of waning immunity at the population level,” she added.
Those for whom the infection was confirmed with a PCR, or polymerase chain reaction, test had a less pronounced decline in antibodies, compared to those who had been asymptomatic and unaware of their infection.
The study backs up findings from similar surveys in Germany that found the vast majority of people didn’t have antibodies — and that antibodies might fade among those who do, according to Reuters.
A World Health Organization spokesman said that uncertainty over how long immunity would last and the fact that most people had never had antibodies against the disease in the first place showed the importance of breaking transmission chains.
“Acquiring this collective immunity just by letting virus run through the population is not really an option,” Tarik Jasarevic told a UN briefing in Geneva.
see also Coronavirus antibodies could last for at least four months and... Barclay noted that the rapid decrease in antibodies did not necessarily have implications for the efficacy of vaccine candidates undergoing clinical trials.
“A good vaccine may well be better than natural immunity,” she said.
The study also found that younger people who have recovered from the disease had a slower loss of antibodies, compared to survivors older than 75, according to CNN.
Still, not enough is known to determine if antibodies provide any effective level of immunity or how long people may be immune to reinfection with the illness.
The study also did not use samples from the same people over and over again, but from different people over time – and it’s possible that people who had been exposed to the bug were less likely to take part over time and that may have skewed the results, researchers noted.

Most experts would agree that it is not an option to let the virus infect a community and hope that people in that community would then have antibodies protecting them against the coronavirus.
Health experts worldwide are not sure how long immunity does last and that the only real choice that nations (and tribal communities) face is to work to break transmission chains.
That is until an effective vaccine is found.
One of the questions being asked is whether a natural immunity to the virus occurs (especially in a person who has had it) and how strong it may be compared to a good vaccine.
After the first wave of infections in Europe, in March and April of this year, scientists at Imperial College in London have tracked antibody levels in the population.
What they found was that what is called antibody prevalence fell from June to September and what that signaled is that there may be decreasing population immunity and decisions were made to enforce new lockdowns as they face a second wave of infections.
This goes against what those who have been infected and have recovered are hoping, that there is protection after an infection and that is long lasting.

 Collective immunity: WHO does not plan to let Covid-19 circulate freely - Teller Report Teller Report Now you can see non-English news...
Collective immunity: WHO does not plan to let Covid-19 circulate freely 2020-10-13T06:39:17.317Z The WHO deemed it unthinkable on Monday to let the Covid-19, whose case fatality rate is higher than that of the flu, circulate freely so that the population has access, as some have suggested ... For the World Health Organization (WHO), the free circulation of Covid-19 is not a possible option in order to achieve collective immunity.
"Never in the history of public health has collective immunity been used as a strategy to respond to an epidemic, and even less to a pandemic.
It is scientifically and ethically problematic", declared Monday 13 October WHO Director General Tedros Adhanom Ghebreyesus at a press conference.
Seroprevalence surveys suggest that in most countries, less than 10% of the population has been infected," said Tedros Adhanom Ghebreyesus for his part.
He also explained that the world did not know enough about the immunity enjoyed by people who contracted Covid-19, pointing out that some individuals have been newly infected.
"Most people infected with the virus develop an immune response within the first few weeks, but we don't know if this response is strong or long-lasting, or if it differs from person to person," he said.
He underlined that the concept of collective immunity is used in vaccination campaigns and he recalled that for smallpox it is necessary that 95% of the population be vaccinated so that the remaining 5% are protected.
Tedros Adhanom Ghebreyesus acknowledged that "there have been discussions about the concept of achieving so-called collective immunity by letting the virus spread."
Thus, in several countries, a certain part of the population, such as in Germany, tired of the epidemic control measures put in place by governments such as the compulsory wearing of masks, loudly calls for their repeal.
But "collective immunity is obtained by protecting people against a virus, and not by exposing them to it", hammered the head of the UN agency.
About forty vaccine candidates No vaccine against Covid-19 has been approved worldwide, but several pharmaceutical companies have launched clinical trials.

It was thought that when a large portion of a community had been exposed to Covid, its spread became far less likely.
Related articles University of Sao Paulo researchers suggested that a drastic fall in COVID-19 deaths in Manaus pointed to collective immunity at work, but they now believe that antibodies to the disease after infection may not last more than a few months.
Local authorities on Friday enforced a 30-day ban on parties and other gatherings, and restricted restaurant and shopping hours, a setback for the city of 1.8 million after the worst of the pandemic seemed to be behind them.
Non-essential businesses were closed but many simply ignored social distancing guidelines.
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The study by the University of Sao Paulo's Institute of Tropical Medicine tested newly donated banked blood for antibodies to the virus and used a mathematical model to estimate contagion levels.
The high infection rate suggested that herd immunity led to the dramatic drop in cases and deaths, the study said.
Daily burials and cremations fell from a peak of 277 on May 1 to just 45 in mid-September, according to the mayor's office.
But now the numbers are on the rise again.
Brazil's right-wing President Jair Bolsonaro (Image: Getty) The study's lead researcher, Ester Sabino, declined to be interviewed for this article because the Manaus herd immunity study awaits peer review for publication.
Authorities warned Manaus residents they were ignoring the virus and risked a second wave of contagion by not wearing masks, packing into bars and attending parties.
Epidemiologist Dr André Patricio Almeida, of the Adventist Hospital of Manaus, said cases are rising again mostly among younger, wealthier people who go to bars who show milder symptoms but often infect older relatives who need to be treated in hospital.
Almeida said too little is known about COVID-19 and whether re-infection is possible to verify if herd immunity was reached in Manaus, but some short-lived immunity probably had been attained.
"There could be immunity that does not last for long," Mayor Virgilio agreed.

 Coronavirus: What is herd immunity and how will it help protect us from Covid-19?
- Mirror Online Coronavirus: What is herd immunity and how will it help protect us from Covid-19?
With Boris Johnson's government stepping up the UK's response to the coronavirus pandemic to the delay phase, the term 'herd immunity' is likely to become more common By SEO Editor Video Loading Video Unavailable Click to play Tap to play The video will auto-play soon 8 Cancel Play now Get our daily coronavirus email newsletter with all the news you need to know direct to your inbox Sign up When you subscribe we will use the information you provide to send you these newsletters.
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Thank you for subscribing We have more newsletters See our Invalid Email Herd immunity is a phrase that is likely to be discussed more widely in the coming days and weeks.
It’s one of the ways the government is planning to reduce the impact of which has so far killed 10 people in the UK and infected 590.
The delay phase involves the potential closure of schools and postponing or even cancelling large events.
But it’s also expected that during this period, we’ll hear the term ‘herd immunity’ on a more regular basis.
The government is expected to increase the UK's coronavirus response from the contain phase to delay (Image: Anadolu Agency via Getty Images) Read More Related Articles Read More Related Articles Herd immunity is when a to an infection.

 Coronavirus: can herd immunity really protect us?
Éditions France L’expertise universitaire, l’exigence journalistique Facundo Arrizabalaga/EPA Coronavirus: can herd immunity really protect us?
Partenaires de The Conversation France The UK government recently enacted its second phase of response to the COVID-19 pandemic: .
According to ITV journalist , the government’s strategy to minimise the impact of COVID-19 “is to allow the virus to pass through the entire population so that we acquire herd immunity, but at a much delayed speed so that those who suffer the most acute symptoms are able to receive the medical support they need, and such that the health service is not overwhelmed and crushed by the sheer number of cases it has to treat at any one time”.
At face value, this seems like a sound strategy, but what exactly is herd immunity and can it be used to combat COVID-19?
But if enough people develop an immune memory, then the disease will stop spreading, even if some of the population is not immune.
This is herd immunity, and it is a very effective way to protect the whole of a population against infectious disease.
But herd immunity is typically only viewed as a preventive strategy in vaccination programmes.
If we don’t have a vaccine – as we don’t for COVID-19 – achieving herd immunity would require a significant proportion of the population to be infected and recover from COVID-19.
So what would this mean for the spread of the disease in the UK?
The percentage of the population that needs to be immune to enable herd immunity depends on how transmissible a disease is.
This is measured by the term R0, which is how many new infections each case will generate.
For COVID-19, the , though studies are still ongoing and this number will probably change.
This means that for herd immunity, about 70% of the UK population would need to be immune to COVID-19.
Achieving herd immunity would require well over 47 million people to be infected in the UK.
Current estimates are that COVID-19 has a .
This means that achieving herd immunity to COVID-19 in the UK could result in the deaths of more a million people with a further eight million severe infections requiring critical care.
Novel coronavirus in 3D by Fusion Medical Animation.
A delay strategy when combined with surveillance and containment, , could be very effective in combating the spread of COVID-19.
Yet if we slow the spread of the virus but are relying on herd immunity to protect the most vulnerable people, we would still need 47 million people to be infected.
Even if we manage to protect the most vulnerable people (though no discussion is provided on how this will be done or for how long) the fatality rate for the otherwise healthy portion of the population may still be .
We can and we must do better than that.
China is rapidly controlling the spread of COVID-19 without requiring herd immunity ( ).
Waiting for herd immunity to COVID-19 to develop in the UK by letting the virus “ ” is not a good public health strategy.

 Herd immunity: will the UK's coronavirus strategy work?
Search with google More Herd immunity: will the UK's coronavirus strategy work?
Ministers look to have given up on containment in favour of a novel approach some experts are wary of Fri 13 Mar 2020 18.23 GMT Last modified on Wed 1 Jul 2020 18.16 BST Play Video 1:46 Coronavirus: Johnson warns 'many more families are going to lose loved ones' – video Herd immunity is a phrase normally used when large numbers of children have been vaccinated against a disease like measles, reducing the chances that others will get it.
As a tactic in fighting a pandemic for which there is no vaccine, it is novel – and some say alarming.
Generally it is thought that those who recover will be immune, at least for now, so they won’t get it twice.
But allowing the population to build up immunity in this way – rather than through widespread testing, tracking down the contacts of every case and isolating them, as many other countries in Asia and Europe have chosen to do – could increase the risk to the most vulnerable: older people with underlying health problems.
To reach herd immunity, about 60% of the population would need to get ill and become immune, according to Sir Patrick Vallance, the government’s chief scientific adviser.
While this containment approach is clearly difficult (and may be impossible for many countries), it does seem a worthy goal; and those countries that can should aim to do.” The government’s “nudge unit” seems to favour this strategy.
Dr David Halpern, a psychologist who heads the Behavioural Insights Team, said on BBC News: “There’s going to be a point, assuming the epidemic flows and grows, as we think it probably will do, where you’ll want to cocoon, you’ll want to protect those at-risk groups so that they basically don’t catch the disease and by the time they come out of their cocooning, herd immunity’s been achieved in the rest of the population.” But Anthony Costello, a paediatrician and former World Health Organization director, said that the UK government was out of kilter with other countries in looking to herd immunity as the answer.
It could conflict with WHO policy, he said in a series of Twitter posts, which is to contain the virus by tracking and tracing all cases.
He quoted Dr Tedros Adhanom Ghebreyesus, the WHO director general, who said: “The idea that countries should shift from containment to mitigation is wrong and dangerous.” Herd immunity might not even last, Costello said.
“Does coronavirus cause strong herd immunity or is it like flu where new strains emerge each year needing repeat vaccines?

It's not an option for handling the pandemic, says the World Health Organization.
By Claire Gillespie and Updated October 14, 2020 Advertisement ellipsis More A concept bandied about early in the coronavirus pandemic, something called "herd immunity," has surfaced again.
President Trump referenced the idea during an last month, insisting the virus would eventually go away as people develop "a herd mentality."
(Okay, he misspoke, but we think we know what he meant.)
Then, during a on the nation's pandemic response, Senator Rand Paul (R-Kentucky) tussled with Anthony Fauci, MD, the nation's leading infectious disease expert, over whether "community immunity" is responsible for New York City's currently low infection rate.
"They’re no longer having the pandemic because they have enough immunity in New York City to actually stop it," asserted the state's junior senator.
Dr. Fauci, a member of the White House Coronavirus Task Force, forcefully pushed back, arguing that New York's low positivity rate reflects its adherence to task force recommendations, including the use of masks and social distancing, not herd immunity.
Now the head of the World Health Organization (WHO) is weighing in with a strong rebuke.
On Monday, Director-General Tedros Adhanom Ghebreyesus said reaching herd immunity by letting the virus spread throughout the population would be "simply unethical," resulting in unnecessary suffering and death.
"Never in the history of public health has herd immunity been used as a strategy for responding to an outbreak, let alone a pandemic.
It is scientifically and ethically problematic," he said.
So what is herd immunity, anyway, and how does it relate to COVID-19?
RELATED: Herd immunity (also known as community immunity) is defined by the (CDC) as “a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely.” In other words, where herd immunity exists—when lots of people in an area are vaccinated or have already been infected with a disease—fewer people get sick and fewer germs are able to spread from person to person.
RELATED: The theory is that when someone gets vaccinated, it’s not only that person who is protected from infection but others too, because that individual cannot transmit the disease in the community.
In that way, herd immunity protects people who cannot be vaccinated, people whose immune systems aren’t strong enough and are therefore the most vulnerable to serious illness.
A late 1980s measles outbreak among preschool-age children in the US serves as an example of herd immunity via vaccination.
who examined the association between incidence of measles and immunization among preschool-age children concluded that immunizing about 80% of the population may be enough to stop sustained measles outbreaks in an urban community.
In the context of COVID-19, developing herd immunity would mean protecting the most vulnerable citizens while letting most everyone else catch, and hopefully recover from, the virus.
RELATED: Allowing people to contract COVID-19—Is that a good idea?
Sweden famously eschewed a lockdown approach in favor of allowing people to take personal responsibility for their health.
But as the authors of a recent commentary published by the point out, "herd immunity is nowhere in sight."
Rates of infection, hospitalization, and death per million people are much higher than in neighboring Scandinavian countries, they report.
WHO's Ghebreyesus makes it clear that herd immunity is something that's achieved when a certain threshold of vaccination is reached against a virus in a population.
"In other words, herd immunity is achieved by protecting people from a virus, not by exposing them to it," he said.

 Collective immunity of new corona achieved with 43% of population acquisition - Teller Report Teller Report Now you can see non-English news...
Collective immunity of new corona achieved with 43% of population acquisition 2020-06-23T20:33:33.132Z [NHK] American scientific magazines have talked about "collective immunity", where many people acquire immunity to the new coronavirus, which prevents the spread of infection.
Collective immunity of the new corona achieved with acquisition of about 43% of the population American scientific magazine June 24 5:22 About "collective immunity" that many people acquire immunity to the new coronavirus and the infection does not spread, an American scientific magazine may be achieved if approximately 43% of the population acquires immunity Published a paper.
However, this scientific journal continues to call for the importance of infection control, assuming that each country is not in the current state of achieving collective immunity.
Research groups in the United Kingdom and Sweden theoretically wonder how much of the population can achieve "immunity immunity" when the majority of the population acquires immunity and the infection does not spread if the new coronavirus is acquired.
As a result, it was found that if 43% of the population acquired immunity, they could achieve "collective immunity" that would prevent further spread of the infection.
I'm guessing that it will spread to.
The conventional guess is that 60% of people need to acquire immunity, which means that it is possible to obtain even a smaller ratio.
However, the research group says that this conclusion is "not to make precise predictions."
Also, the editorial department of the scientific journal "Science", which published the article, said that he was concerned that the importance of infection control would be neglected, saying, "Even if 43% can achieve collective immunity, No country has reached that level," he said, calling for continued measures such as avoiding contact with people.
Source: 2020-06-23T20:33:33.132Z 2020-09-27T19:17:38.890Z 2020-05-29T08:05:51.245Z 2020-10-04T19:11:55.365Z 2020-05-05T07:06:31.350Z 2020-08-20T00:55:14.167Z 2020-04-30T07:11:25.233Z 2020-07-24T21:43:17.383Z 2020-07-17T10:36:33.245Z 2021-01-13T00:28:53.727Z 2021-01-12T23:48:59.727Z 2021-01-12T16:20:07.416Z 2021-01-12T17:29:51.523Z 2021-01-13T00:08:53.406Z 2021-01-12T18:19:16.709Z 2021-01-13T01:09:29.585Z 2021-01-12T19:19:22.019Z 2021-01-13T06:29:52.732Z 2021-01-13T08:29:18.407Z 2021-01-13T15:49:40.156Z 2021-01-13T15:49:05.417Z 2021-01-13T15:48:42.030Z 2021-01-13T15:38:53.714Z 2021-01-13T15:38:47.985Z © Communities 2019 - ↑↑ x

 Immunity to coronavirus is 'fragile' and 'short lived,' expert warns Menu Search quotes, news & videos Menu Immunity to the coronavirus is 'fragile' and 'short-lived,' immunologist warns Published Mon, Jul 6 2020 11:10 AM EDT Updated Tue, Jul 7 2020 9:04 AM EDT Share Share Article via Facebook Share Article via Twitter Share Article via LinkedIn Share Article via Email VIDEO 3:53 03:53 Immunity to Covid-19 'looks rather fragile,' professor warns It is not a "safe bet" to rely on immunity to as a strategy for coping with the pandemic, one expert has warned, adding that herd immunity strategies were "probably never going to work."
Speaking Monday on CNBC's " ," Danny Altmann, professor of immunology at Imperial College London, said that in towns and cities where there had been coronavirus infections, only 10% to 15% of the population was likely to be immune.
"And immunity to this thing looks rather fragile — it looks like some people might have antibodies for a few months and then it might wane, so it's not looking like a safe bet," he said.
"It's a very deceitful virus and immunity to it is very confusing and rather short-lived."
He also raised questions about the likely success of so-called herd immunity — when a population is allowed some exposure to the virus in order to build immunity among the general population — which has been cited by health officials in Sweden, which .
VIDEO 1:01 01:01 Wondering if insurance will cover the coronavirus—Here's what you need to know Despite a global race to find a vaccine for the coronavirus, experts remain uncertain about whether the antibodies present in people who have had the virus actually provide immunity to reinfection.
Top White House health advisor Dr. Anthony Fauci that if Covid-19 behaved like other coronaviruses, there "likely isn't going to be a long duration of immunity" from antibodies or a vaccine.
Meanwhile, the that it remains unclear whether those who have already caught the virus once will be immune to getting it again.

 Coronavirus: what is herd immunity and why is it so important?
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☰ Coronavirus: what is herd immunity and why is it so important?
Without a vaccination a large enough number of people will have to contract Covid-19 and recover from it By March 13, 2020 11:38 pm Updated July 13, 2020 10:59 am Herd immunity occurs when a high percentage of the population is vaccinated making it difficult for infectious diseases to spread, because there are not many people who can be infected.
For example, , and it will quickly disappear again.
Herd immunity gives protection to vulnerable people such as newborn babies, elderly people and those who are too sick to be vaccinated.
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However, our problem now is that there is no vaccination to protect against coronavirus – and there won’t be one for at least another 12-18 months.
Therefore for the UK population to gain herd immunity, – will need to contract the virus and then recover.
If that situation occurs then people will be less likely to get covid-19 in the future and the public can build up a resistance to it.
Elderly people Elderly people are one of the key groups that rely on herd immunity to protect them, as they are more susceptible to disease.
If they are able to isolate as much as possible during the coronavirus peak, once herd immunity is established isolation measures can be scaled back.
Given Sir Patrick has said he believes will become an “annual virus”, building up herd immunity will be vital.
The only problem is, with no vaccination available, no one knows how long it will take for 60 per cent of the population to be infected, as no country has reached that figure yet.
And as cases in China have slowed markedly to a handful, no country may ever get there given the extreme measures being put in place by those worst affected.
And as points out, herd immunity does not protect against all vaccine-preventable diseases.
The best example of this is tetanus, which is caught from bacteria in the environment, not from other people who have the disease.

According to the government’s chief scientific adviser, we might have to reacquaint ourselves with the concept.
Because to control coronavirus, says Patrick Vallance, will require something called “herd immunity”.
It will also require controlling who in the herd it is who gains that immunity.
Sponsored Herd immunity does not require everyone in Britain’s “herd” to be infected.
It happens before that, when just a proportion of them have.

 What is herd immunity and can it stop the coronavirus?
Expand menu Expand menu What is herd immunity and can it stop the coronavirus?
This story was part of our May 2020 issue If the virus keeps spreading, eventually so many people will have been infected and (if they survive) become immune that the outbreak will fizzle out on its own as the germ finds it harder and harder to find a susceptible host.
This phenomenon is known as herd immunity.
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Those figures aren’t a random guess.
They are informed by the point at which epidemiologists say herd immunity should kick in for this particular virus.
Last week the herd immunity idea blew up in the headlines after UK prime minister Boris Johnson indicated that country’s official strategy might be to put on a stiff upper lip and let the disease run its course.
The chief science adviser to the UK government, Patrick Vallance, said the country needed to “ so more people are immune to this disease and we reduce the transmission.” Yesterday, the prime minister of the Netherlands, Mark Rutte, , saying, “We can slow down the spread of the virus while at the same time building group immunity in a controlled way.” But shooting for herd immunity right away would be a disastrous strategy, according to the newest models.
That’s because so many people will become severely ill—and a sudden boom in sick people needing hospital or ICU care will overwhelm hospitals.
Slowing it down would mean health systems could be spared and lives saved, but ultimately the result could be the same.
That is, even if the pandemic is drawn out over time, it may still take herd immunity to bring it to an end.
As Matt Hancock, the UK Secretary for health and social care, of the UK government: “Herd immunity is not our goal or policy.
It’s a scientific concept.” But what exactly is herd immunity?
When enough of the population is resistant to a germ, its spread stops naturally because not enough people are able to transmit it.
Thus, the “herd” is immune, even though many individuals within it still are not.
Although it is ghastly to contemplate the prospect of billions being infected by the coronavirus, which has an (pdf) (that too is uncertain, and the fatality rate of cases rushed to the hospital is higher), we’ve seen evidence for the emergence of herd immunity in other recent outbreaks.
In a simple model of an outbreak, each case infects two more, creating an exponential increase in disease.
Two years later, in 2017, there was no longer nearly so much to worry about.
found by checking blood samples that 63% of the population in the northeastern beach city of Salvador had already had exposure to Zika; the researchers speculated that herd immunity had broken that outbreak.
Vaccines create herd immunity too, either when given widely or sometimes when administered in a “ring” around a new case of a rare infection.
The coronavirus is new, so it doesn’t appear that anyone is immune to it: that’s what lets it spread and why it can have such severe effects in some people.
For herd immunity to take hold, people must become resistant after they are infected.
That occurs with many germs: people who are infected and recover become resistant to getting that disease again, because their immune system is charged with antibodies able to defeat it.
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Yes No About already, and it’s likely they are now resistant, although the degree of immunity remains unknown.
“I would be surprised, but not totally surprised, if people did not become immune,” says Myron Levine, an infectious disease expert at the University of Maryland.
Some viruses, like the flu, do find ways to keep changing, which is why immunity against such seasonal germs isn’t complete.
The point at which we reach herd immunity is mathematically related to the germ’s propensity to spread, expressed as .
The R0 for the coronavirus is (pdf), meaning each infected person passes it to about two other people, absent measures to contain the contagion.
To imagine how herd immunity works, think of coronavirus cases multiplying in a susceptible population this way: 1, 2, 4, 8, 16, and so on.
But if half the people are immune, half of those infections won’t ever happen, and so the spreading speed is effectively cut in two.
“That is similar to pandemic flu of 1918, and it implies that the end of this epidemic is going to require nearly 50% of the population to be immune, either from a vaccine, which is not on the immediate horizon, or from natural infection,” Harvard University epidemiologist Marc Lipsitch told a gathering of experts on .
The more infectious a virus is, the more people need to be immune for us to achieve herd immunity.
Measles, one of the most easily transmitted diseases with an R0 over 12, requires about 90% of people to be resistant for unprotected people to get a free ride from the herd.
That’s why new outbreaks can start when even small numbers of people opt out of the measles vaccine.
Similarly, if the coronavirus spreads more easily than the experts think, more people will need to get it before herd immunity is reached.
For an has to be immune before the effect kicks in, according to the simplest model.
The basic tactics being urged would be to isolate sick people, try to reduce social contacts by 75%, and close schools.
Those economically costly measures could “Suppressing transmission means that we won’t build up herd immunity,” says Azra Ghani, the lead epidemiologist on the new model of the outbreak from Imperial College London.
The trade-off of success is “that we are driving it down to such a low level that we have to keep those [measures] in place.” Article meta Share Tagged Author Latest content Load more

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Close Main Content The problem with using herd immunity to fight coronavirus The UK's Nudge Unit and Dominic Cummings are weighing up herd immunity as a possible endgame for coronavirus, but the consequences could be severe By 12 Mar 2020 By Thursday 12 March 2020 Boris Johnson and Chief Medical Officer Chris Whitty Getty Images In the UK, the number of confirmed cases keeps on steadily ticking upwards.
As of March 12 it had 590 confirmed infections – a 134 case increase on the previous day.
Up until now the government’s strategy has been simple: first try and contain the outbreak and then delay the spread, evening out the pressure on the NHS.
But now people involved in the government’s coronavirus response appear to be mooting a new strategy: herd immunity.
On March 11, David Halpern – chief executive of the government-owned Behavioural Insights Team and a member of the the Scientific Advisory Group for Emergencies – outlining an approach that depended on shielding vulnerable people until enough of the UK population had been infected with Covid-19 that acquired immunity stopped its spread altogether.
Advertisement On the ITV website, Robert Peston , writing that the strategy of the British government “is to allow the virus to pass through the entire population so that we acquire herd immunity”.
People can gain immunity to diseases after being exposed to them, and once enough people are immune to a disease – either through exposure or vaccines – it will stop circulating within a population.
Italy too is trying similar policies – including banning most public gatherings – although it’s still too early to know whether that has stopped the spread of the disease there.
We contacted the Department of Health and Social Care to clarify whether herd immunity was part of the government's official coronavirus strategy, but it did not respond in time for publication.
But how would herd immunity work in the UK if it is adopted?
Roughly-speaking – given what we know about the current infection rate of Covid-19 – the disease would need to infect approximately half of the UK population until we achieved herd immunity.
Although over 80 per cent of Covid-19 infections are mild – that’d add up to more than six million people at risk of severe symptoms.
And of 44,415 confirmed cases, around five per cent of people experience critical illness: including respiratory failure, septic shock or organ failure.
Advertisement The problem is that embracing herd immunity could well put the NHS under immense strain – depending on how well we were able to shield vulnerable people from the disease.
Jeremy Rossman, a virologist at the University of Kent, isn’t convinced that accepting herd immunity is inevitable.
“Even spread over a period of months [widespread infection] is obviously not an acceptable plan.
Nor is this a necessary or inevitable outcome, especially with good surveillance, containment, delay and social distancing measures enacted.” The example of other countries suggests that herd immunity might not be the only ending point of the coronavirus outbreak.
In South Korea, which recorded 851 new cases in a single day at its peak, the outbreak is slowing.
But while other countries – including Denmark, Spain and the Republic of Ireland – are doubling-down on containment by shutting schools and limiting public gatherings, the UK, or at least some of those close to the government, are leaning in a different direction.
Advertisement Although the UK government is now moving to the of its Covid-19 plan, it’s not clear what role herd immunity will play in this.
What we do know is that it is a keen interest of both the Behavioural Insights Team (the so-called “Nudge Unit”) and Boris Johnson’s chief adviser Dominic Cummings – who brought up the topic in a meeting with UK tech leaders on March 11.

Africa correspondent Fill 2 Copy 11 Created with Sketch.
Monday 11 January 2021 15:09, UK Please use Chrome browser for a more accessible video player Has South Africa acquired 'herd immunity'?
Leading scientists in South Africa believe the country has established a form of collective or herd immunity to COVID-19 after the number of infections unexpectedly plummeted following a major outbreak in June and July.
Commenting on a series of studies revealing the existence of high infection rates in the provinces of Western Cape and Gauteng, the country's leading vaccinologist, Professor Shabir Mahdi, told Sky News that he believed the had stimulated a level of immunity in approximately 12 to 15 million people.
"What has happened in SA today, the only way to explain it, the only plausible way to explain it is that some sort of herd immunity has been reached when combined with the use of non-pharmaceutical interventions... like the wearing of masks, physical distancing, ensuring ventilation when indoors and so on."
More from Covid-19 "Inexplicably, the numbers (of those infected with ) started dropping off at the end of July, and at the time I couldn't explain why," said Dr Hsiao.
"But when we analysed the data it become clear, this immunity within the population level (linked to) the big surge infections is probably the main reason why we've seen the decrease of numbers of infected."
Image: During lockdown residents were forced to queue together for essentials The understanding that South African scientists have reached on the attainment of a level of collective immunity in their country seems to contradict a , London, who found that the number of people with COVID-19 antibodies in the UK declined from 6% of the population in June to 4.4% in September.
Their 'React-2' study suggests that immunity to COVID-19 may be short-lived, but Professor Mahdi challenges the importance of antibody analysis, pointing out that it only evaluates one part of the human body's immune system.
"This waning of antibodies does not really inform what to expect without adequate interrogation of other components of the immune system.
Experience with common cold and SARS coronavirus is that T-cell immunity likely lasts for 2-3 years."
South African researchers believe that South Africa's strict level five lockdown - which was imposed back in March - worked inadvertently to kickstart a massive wave of infection.
"This inadequacy in terms of adherence of the lockdown, where inadvertently we've had transmission taking place, has resulted in a high percentage in densely populated areas becoming immune.
"There might be a question in terms of the duration of immunity... based on our experience with other coronaviruses, a mild infection is probably going to (generate immunity) for two to three years but that places us in a really good position."
Image: Professor Shabir Mahdi says that in South Africa lockdown may have accelerated the spread of the disease For the scientists - and the policy makers - there is a great deal of work to be done and additional studies will be commissioned over the next few weeks with the aim of better understanding the numbers of those infected and how the virus has spread.
But the vaccinology professor clearly believes that the development of some immunity in the population to COVID-19 was not only inevitable - but a necessary development in the South African context.
"It is not denying that COVID is the most important cause of death this year, superseding HIV, TB and everything else but the response needs to be much more nuanced than simply believing that a highly restrictive lockdown is going to get rid of the virus.

 Collective immunity to coronavirus is almost here - CORVID / / Collective immunity to coronavirus is almost here Health and Tips 31 Jul Collective immunity to coronavirus is almost here Share with socials Share by: Some population groups may already be close to achieving “crowd immunity”, despite more or less strict social distancing measures.
An international group of scientists suggested that the herd immunity threshold (HIT) in the new coronavirus may be much lower, not 60-70%, but 10-20% of immune people, and perhaps even less.
Scientists believe that the main reason for the different sensitivity of people to the new coronavirus is that a significant part (from 35% to 80%) of those who are not yet infected with SARS-CoV-2 have T cells, antibodies or other components that appeared in them as a result of a cold suffered in the past due to other “harmless” coronaviruses or flu.
That is, many people already have cross-reactive immunity of varying strength to the new pathogen.
In other words, many of us can fight COVID-19 in one way or another.
Since such antibodies are not specific for SARS-CoV-2, and T cells are difficult to detect at all, these components of immunity are usually not detected by current tests for immunity to the new coronavirus, scientists write.
They note that despite the weakening of various quarantine measures, in some regions there is no significant increase in deaths, and this may be evidence of the correctness of their hypothesis.

A few days earlier, Bill Gates said he expects developed nations to contain the illness by late 2021 as well, once vaccines are widely available.
What vaccines will do, assuming they’re effective and safe, is to hasten the herd immunity phenomenon that would significantly reduce the infection rate while preventing the emergence of massive outbreaks that are hard to manage.
We could get to herd immunity the difficult and painful way, by letting the virus roam free and infect a large percentage of the population.
and found that you’d have to pay a heavy toll.
Many more people would have to die for communities to reach herd immunity via infection.
That said, it turns out that herd immunity might be a lot easier to attain for COVID-19 than initially believed, which could be the great news the world needs right now.
A series of distinct studies, some of which have yet to be peer-reviewed, indicate that COVID-19 immunity is a lot better than we thought.
Even in the absence of antibodies, which are almost undetectable in asymptomatic and mild COVID-19 survivors, that could deal with subsequent exposure to the virus.
While researchers can’t say how long the immunity lasts, there have been no cases of confirmed reinfection in the eight months since it all started in Wuhan.
Herd immunity works when a large enough percentage of the population is protected against an infectious disease via direct exposure or vaccines.
Some say that COVID-19 herd immunity will be achieved once more than 60% or 70% of the population is immune.
Unfortunately, those milestones are extremely difficult to achieve.
But a new study says that percentage may turn out to be much lower than initially believed, as scientists have started observing herd immunity in communities that were hit hard in the early months of the pandemic.
reports that more than a dozen scientists say the threshold might really be around 50%, or maybe even less than that.
If that turns out to be accurate, then the pandemic might be easier to contain, especially once vaccines can be deployed widely.
The estimates are based on “complicated statistical modeling of the pandemic” that take divergent approaches and offer “inconsistent estimates.” Therefore, herd immunity can’t yet be proven for any community.
The Times explains that parts of New York, London, and Mumbai already have “substantial immunity” to the virus.
They’re all large, densely-populated cities.
These scientists realized that the original 60%-70% calculation for herd immunity doesn’t take real-life events into account.
That figure is said to have assumed that each community member has the same susceptibility to the virus, which isn’t the case.
“Herd immunity could vary from group to group, and subpopulation to subpopulation,” Yale Institute for Global Health Dr. Saad Omer said.
A neighborhood of older people might have little contact with other people, but they’d be more likely to die.
The researchers also observed that the virus rushes through densely populated cities, but it’s slower to infect suburban and rural areas.
Once these factors are accounted for in herd immunity studies, the herd immunity percentages fall.
Some researchers say the figure could go as low as 10% to 20%, but those estimates come from a minority of researchers who talked to The Times .
If the first coronavirus wave infects the most susceptible people, immunity could be achieved even more efficiently than with a vaccination campaign, said Stockholm University mathematician Tom Britton.
His model says that 43% is enough for herd immunity.
They found that between 51% and 58% of residents in poor areas had antibodies, but that figure dropped to between 11% and 17% in other places in the city.
While researches are far from declaring herd immunity for these cities or neighborhoods, these locations have not seen additional surges in cases since the first wave.
It’s still unclear how immunity lasts or how a subsequent reinfection would impact an individual once immunity wanes.
Also, regardless of the model chosen to map herd immunity, there’s one huge thing that’s not exactly addressed in any of the experiments The Times mentioned.
Not all patients who recover from COVID-19 have high levels of neutralizing antibodies in their bloodstreams, and they might get false negatives in antibody surveys.
This would directly impact herd immunity conclusions, but in a good way.
The number of infected people in a community could be much higher than what researchers can prove with existing antibody tests.
Also, immunization campaigns could use validated data from these studies to target specific groups of people and prevent future outbreaks.
On a related note, if COVID-19 herd immunity is reached at a lower percentage than initially believed, then even a vaccine that’s just 50% effective might be good enough for public use in the first immunization stages.
Dr. Antohony Fauci said he hopes vaccine efficacy will surpass 75% while cautioning that we won’t know the figure until Phase 3 trials are complete.
The Times’ full report on COVID-19 herd immunity is worth a read, and it’s available .
Tags: , Chris Smith started writing about gadgets as a hobby, and before he knew it he was sharing his views on tech stuff with readers around the world.

Coronavirus: Experts cast doubt on UK plan for ‘herd immunity’ ‘We really don’t know whether there will be herd immunity or not,’ says head of virology at National Institute for Biological Standards and Control Health Correspondent Friday 13 March 2020 15:31 Article bookmarked Find your bookmarks in your section, under my profile Don't show me this message again ✕ Experts have cast doubt on the government’s policy of letting large numbers of the British population catch in a bid to create "herd immunity", warning it may not work and people could be susceptible to catching it again.
On Friday, the UK’s said a level of herd immunity – where a significant proportion of people recover and become immune to the infection – was desirable and could protect the public in the event the virus became a seasonal infection.
He told Sky News: “Communities will become immune to it and that’s going to be an important part of controlling this longer term.
“About 60 per cent is the sort of figure you need to get herd immunity.” Read more But leading scientists and officials warned there is no guarantee people will become permanently immune to the virus, and said it is too soon to know what could happen as the virus spreads through the population.
Dr Nicola Rose, head of virology at the National Institute for Biological Standards and Control, said: “Obviously contain and delay is the approach being taken in the UK and in a number of different countries.
This may well be the case here.
We really don’t know whether there will be herd immunity or not.
Please enter your email address Please enter a valid email address Please enter a valid email address SIGN UP Thanks for signing up to the News newsletter {{#verifyErrors}} {{message}} {{/verifyErrors}} {{^verifyErrors}} {{message}} {{/verifyErrors}} The Independent would like to keep you informed about offers, events and updates by email, please tick the box if you would like to be contacted Read our full mailing list consent terms The Independent would like to keep you informed about offers, events and updates by email, please tick the box if you would like to be contacted Read our full mailing list consent terms “As the virus goes through a population, people may start to develop their own immunity.
It is early days really with this virus to understand what that looks like.
I think we’re a long way from what we would technically call herd immunity.” She said it would only be after people had been infected and their immune response analysed that the true picture could be established around whether people were immune to further infection.
Professor Hanneke Schuitemaker, global head of viral vaccine discovery for Janssen Vaccines, said: “We don’t know how long natural immunity will last.
And if people who have experienced the infection will be protected forever thereafter or whether we will need vaccines to support them that gives continuous protection against reinfection.” On the variation between different countries’ attitudes on how best to tackle the virus, she added: “I think all governments should look at countries where measures have failed and try to do better.
And that’s why I don’t understand why we don’t have a European approach.” More about 1 /1 Coronavirus: Experts cast doubt on UK plan for ‘herd immunity’ Coronavirus: Experts cast doubt on UK plan for ‘herd immunity’ ‘We really don’t know whether there will be herd immunity or not,’ says head of virology at National Institute for Biological Standards and Control Comments Share your thoughts and debate the big issues ✕ About The Independent commenting Independent Premium Comments can be posted by members of our membership scheme, Independent Premium.
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Studies looking for antibodies in community surveys suggest that in most of Europe and North America a far smaller proportion of people have anti-Covid antibodies than what we see in developing world settings like India and Africa, including South Africa.
This implies that there is currently more immunity here and people have been wondering out loud whether we have sufficient ‘herd immunity’ to avoid our own ‘second wave’, and for how long.
There is a lot of jargon and technical discourse on such questions, framed in the language of mathematics and ‘dynamical modelling’.
We can, however, unpack the key concepts in accessible ways that people will hopefully find useful.
Herd vs individual First, what is non-herd, for example, ‘individual’ immunity?
To say I am immune to measles, or Covid-19, is to say that I am not at risk of being infected, even if I come into contact with sources of infection.
Do I get to claim immunity by carefully dodging the really infectious exposures, or do I need to be able to avoid infection even if I am literally thrust into a crowd of people deliberately spluttering on me for hours on end?
Precisely what I am immune to, and under what circumstances, can be tricky to define.Let us say I get a dose of a vaccine, and then avoid infection for two years, after which I get infected.
Did I ‘have’ this thing called ‘immunity’ which I subsequently ‘lost’?
was I merely lucky to avoid infectious exposures for two years, even though the vaccine did nothing for me, or did I have partial immunity all along, but less and less over time, and eventually my number came up?
The flip side of immunity is susceptibility, and being susceptible does not mean one is guaranteed to be infected if some minimal exposure occurs.
The idea that someone may ‘have’, or ‘lack’ ‘immunity’ is not absurd, but it is slippery.
Humans are on some continuum from highly susceptible to highly immune, but it is not obvious that we can summarise this with a single number.
Collective immunity Now, is there a sensible way to talk about ‘collective immunity’, or ‘collective susceptibility’?
In fact, there are many ways we could try to define such a thing.
We could just try to recycle some definition of ‘individual immunity’ and ask how many, or what proportion of a population have it.
This would not help us much, because it tells us nothing about who has the immunity, and what various people in the population do by interacting with each other, and how this contributes to the outbreak growing or receding.
No one has yet seriously suggested that the reproductive number can be stuck onto a country, or a city, or even a neighbourhood like a vintage or cultivar label can be stuck onto a bottle of wine.
Collective susceptibility, and its inverse, collective immunity, are constantly changing.
In colder weather, people spend more time indoors.
Under lockdown, they encounter few people outside their families.
Depending on rules and norms, people adopt various levels of mask wearing and hand sanitising and crucially, as the case counts grow and people recover, many people get individual immunity, at least for a while.
Daily case counts jump around like stock prices, but broadly they slowly go up and down as we ride the ripples and ‘waves’ of the epidemic.
Herd immunity So what is herd immunity then?
It is essentially the state of affairs when ‘collective susceptibility’, also known as the reproductive number, is less than one.
In a population that currently has some infections, to say that there is herd immunity is just a sophisticated sounding way of saying that infections are on the decline.
In a population where there are currently no infections, saying that there is herd immunity expresses that you would expect any new outbreak to fizzle out.
Would you replace a thermometer with a device that simply said whether it is ‘hot’ or ‘cold’ or do you like to know the temperature?
When we have plausible estimates of the reproductive number, or collective susceptibility/immunity, which vary smoothly over a range of values, we do not make progress by forgetting the actual number and just recalling whether it is larger or smaller than one.
It matters greatly whether it is 1.2 or 5; and it matters greatly what we are currently doing to manage collective susceptibility, and what cards we still have left to play.In short – the Covid-19 pandemic is coming and going in ripples and waves, and perhaps there are even features that look like tides.
The authorities should also be attentive and reasonable.
There is, however, not only little point or comfort in ‘herd immunity’ – there is in fact very little meaning in it beyond taking a coarser look at what we should all be keeping a closer eye on in any case.How then to face the imminent future of the Covid-19 pandemic?
Higher proportions of people with detectable antibodies must mean higher levels of collective immunity - all other things being the same.
While it is not wrong to hope that we can breathe a little between waves, we cannot predict much, and we must expect further swells.
Alas, an end to the pandemic requires the interplay of tolerable/sustainable precautionary habits and sufficiently widespread individual immunity.
Unfortunately we don’t know how durable individual immunity really is, either after infection or the use of some vaccine.
So, we are stuck for the foreseeable future with working on our collective immunity mainly through tolerable habits of infection control.
An eye on estimates of the reproductive number gives us about as much hard information as we can hope to have, about what we could possibly mean by collective immunity.

People imprisoned in homes are wondering when the corona crisis will end!
Meanwhile, a report has come that if people develop herd immunity, that is, it will prove to be important in combating corona.
It is known that diseases like polio and smallpox have also been defeated by increasing herd immunity through a vaccine.
According to a report, Britain's Chief Scientific Advisor Sir Patrick Valence advised the government to reduce the impact of the coronavirus by spreading it to a large population, so that the 'herd immunity', a collective immunity, would develop and corona To be finished.
However, the UK Health Ministry denied that no such decision has been taken by the government yet.
UK Health Ministry spokesman Matt Hancock has said that mass deterrence is a natural by-product of any epidemic.
That is, with the outbreak of the epidemic, herd immunity develops in people on their own.
The best example to understand herd immunity is polio.
The whole world was frightened by this disease that disabled people, but almost all the population of the world including India has become immune from polio.
What is herd Immunity: Herd immunity is a very old process of medical science, in which more than 60 percent of the population of the country has to be infected with the virus so that their body becomes immune to fight this virus and in the future, this virus infection will not spread in them.
According to the Center for Disease Control and Prevention, herd immunity is developed by vaccination or infection.
By adopting this, the chain of the spread of the disease in a society or group can be broken.
How does it work: In order to develop herd immunity, the first way is to find out the spread of the disease and the necessary herd immunity limit.
Epidemiologists use the RO, the basic fertility standard, to find the limit.
If vaccination is the method of vaccination, it may take a very long time.
According to experts, the same people can be included in this process, within which there can be continuous development of immunity.
In this case, it may take too long to use herd immunity.
If there is pressure on scientists to adopt herd immunity against this dangerous coronavirus, then it will be able to do the right thing, there is no evidence nor inference can be made.
British virologist (virologist) Dr. Jeremy Rossman says vaccines are not available to protect people against the coronavirus, so herd immunity may not be a good public health strategy.

Asked whether professionals have now given priority to the economy, given that "borders are opening too early and we may have imported cases of coronavirus" - Grujicic said that it is possible that professionals wanted to look at the economic aspect at this time, but noted that we are safe.
Dr. Grujicic claims that we have acquired collective immunity.
Video: The second wave is unavoidable in the fall, but not with this intensity.

 Coronavirus: Was Sweden right?
Study suggests 'significantly higher' Covid-19 immunity Michael Daly 15:01, Jul 02 2020 ITN Britain's Director of Health Improvement, Professor John Newton, says that the science on coronavirus immunity "is still uncertain".
A new study in Sweden is raising hopes immunity to Covid-19 among the public is “probably significantly higher” than has been suggested by the results of testing for antibodies of the disease.
Sweden has taken a less stringent approach than many other countries to restricting the spread of the Sars-CoV-2 coronavirus that causes Covid-19.
The Swedish approach has widely been described as herd immunity, although the country’s health officials don’t describe it that way.
Jonas Ekstromer/TT News Agency via AP Sweden's Minister for Health and Social Affairs Lena Hallengren, centre, looks on as health worker Gun Bjorling administers a Covid-19 test at a drive-in-test station in Alvsjo, Stockholm (file image).
Those who developed COVID-19 were much more likely to die within a month than people without cancer who got it, two studies found.
(/National Institutes of Health via AP) The researchers analysed samples from 203 people and said their results indicated roughly twice as many people had developed Covid-19 immunity through T-cells, than had developed detectable antibodies.
T-cells are a type of white blood cell specialised in recognising virus-infected cells, and are an essential part of the immune system.
In those with milder symptoms it was not always possible to detect an antibody response, but many still showed a marked T-cell response.
T-cell immunity was also found in people who had no Covid-19 symptoms but who had been exposed to family members known to be infected.
T-cell analyses were more complicated to perform than antibody tests and only done in specialised laboratories, the release said.
“Our results indicate that public immunity to Covid-19 is probably significantly higher than antibody tests have suggested,” Professor Hans-Gustaf Ljunggren, from the Centre for Infectious Medicine at the Karolinska Institutet, and a co-senior author of the study, said.
”If this is the case, it is of course very good news from a public health perspective.” AL JAZEZERA California, Texas and many other US states have reported record increases in new coronavirus cases.
An on the server bioRxiv, and has yet to be peer reviewed.
The article said that without a vaccine for Covid-19, it was critical to determine whether exposed and infected people – specially those without symptoms or only very mild forms of the disease – developed robust immunity.
The T-cell response to Sars-CoV-2 was similar to the reaction seen to successful vaccines for other infections, the report said.

 Nuke Pro: Herd Immunity: Collective Unconscious Programming of T-Cells, And The Sweden Discussion Exposing Truth - Sign up as a Follower Pages Please share far and wide!
Search This Blog Wednesday, October 7, 2020 Herd Immunity: Collective Unconscious Programming of T-Cells, And The Sweden Discussion stock here: Maybe it was April this year 2020, when I "discovered" that populations never get anywhere near to the low ball herd immunity level of 60%, Fauci would have you believe 80% (unless you have a vaccine).
And yet the corona-viruses fizzle out, never come back except for a very localized flare up.
By July, the epidemic wave in Sweden was rolling away, and even the lockdown-loving New York Times had to admit that Sweden was "in significantly better condition than the United States."
Today, by all appearances, Sweden has reached a high level of herd immunity.
We were told by the likes of Anthony Fauci that natural herd immunity could not possibly be achieved or considered an endgame solution to the SARS-CoV-2 pandemic because to get there would require accepting a cost of millions of COVID-19 deaths, with a herd immunity threshold requiring 60% or more of the population to become infected.
Serological studies in Sweden show that no more than 20% of the population in Sweden has been infected so they are very far from herd immunity, Fauci argues!
His position should have completely discredited him as an "expert" because the fallacies underlying his assessment have long been illuminated by the scientific community.
There are two main explanations that I'm aware of for how the herd immunity threshhold could be much lower than the doomsdayers have been saying from the start, which together can explain how it could be that Sweden has already achieved.
The first is that the modelers and other doomsdayers failed to consider individuality in transmission dynamics.
Rather, there is a great deal of heterogeneity in transmission dynamics that Fauci and others have failed to take into account, such that once the pool of those most likely to catch and spread the virus has been sufficiently depleted, the virus will simply not be able to spread so easily anymore because, for whatever reason, most of us do not share the characteristics of the "superspreader".
The second explanation is that there is already some background immunity to SARS-CoV-2.
Whereas Fauci touted studies indicating that most of Sweden's population has no evidence of antibodies to SARS-CoV-2 as proof that most of its population remain susceptibles, the truth is that an absence of detectable SARS-CoV-2-specific antibodies is not evidence of susceptibility to infection.
This is because antibodies are neither always sufficient nor even necessary for immunity, and in the case of SARS-CoV-2, many studies now have shown that cell-mediated immunity, as opposed to antibody or humoral immunity, plays just as important -- or, arguably, an even more important -- role.
Numerous studies have shown that even people who have never been exposed to SARS-CoV-2 may still have some level of cross-protective immunity due to past exposure to common coronaviruses (which are a common cause of common colds worldwide).
That is, the immunity gained by infection with a common-cold-causing virus is not only protective against that particular coronavirus, but, evidently, also against the related coronavirus that causes COVID-19, which, as it turns out, is not nearly so "novel", immunologically, as originally assumed.
As a result of the heterogeneity in transmission dynamics and the existing background immunity, the threshold for achieving natural herd immunity is far lower than the doomsdayers keep claiming.
So those of us who've argued from the start that natural herd immunity is a better strategy than the "lockdown until we can mass vaccinate the global population" endgame have science on our side.
We must stand up and fight the authoritarianism and the fearmongering that is used to manufacture consent for policies that both violate fundamental human rights and cause massive harms.

Search with google More This article is more than 9 months old I’m an epidemiologist.
When I heard about Britain’s ‘herd immunity’ coronavirus plan, I thought it was satire This article is more than 9 months old Vulnerable people should not be exposed to Covid-19 right now in the service of a hypothetical future • Sun 15 Mar 2020 12.33 GMT Last modified on Wed 1 Jul 2020 18.15 BST Patients in a temporary overflow building at Brescia hospital, Italy.
‘In Italy, the choices of whom to save and whom to allow to die are real.’ Photograph: Miguel Medina/AFP via Getty Images Y our house is on fire, and the people whom you have trusted with your care are not trying to put it out.
Britain goes it alone over coronavirus.
The stated aim has been to achieve “herd immunity” in order to manage the outbreak and prevent a catastrophic “second wave” next winter – even if Matt Hancock has tried to put that .
A large proportion of the population is at lower risk of developing severe disease: roughly speaking anyone up to the age of 40.
So the reasoning goes that even though in a perfect world we’d not want anyone to take the risk of infection, generating immunity in younger people is a way of protecting the population as a whole.
Play Video 1:05 WHO director general: Europe is now at centre of coronavirus pandemic – video We talk about vaccines generating herd immunity, so why is this different?

Chief Scientific Adviser Sir Patrick Vallance warned COVID-19 is likely to become a "seasonal virus" as he said the UK will only benefit from indirect protection, the so-called herd immunity, from the coronavirus if 60 percent of the population becomes infected.
Asked how many Britons will need to get coronavirus before herd immunity comes into play, Sir Patrick said: "Probably about 60 percent or so.
Related articles "60 percent is the sort of figure you need to get herd immunity.
"We think this virus is likely to be one that comes back year on year, become like a seasonal virus."
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Patrick Vallance said 60 percent of Britons must get the virus for herd immunity to kick in (Image: SKY NEWS) "The second is, of course, protect the elderly and the vulnerable to make sure, during that peak, they are protected."
Herd immunity is where the spread of a contagious disease is stopped due to a high proportion of individuals, but not necessarily all, becoming immune to the disease.

 Coronavirus: Focusing on Collective Immunity by Letting the Covid-19 Circulate "is Not an Option", According to the WHO - chb44.com - Life in France Wednesday, January 13, 2021 The latest news and views from France written in English Search for: Coronavirus: Focusing on Collective Immunity by Letting the Covid-19 Circulate “is Not an Option”, According to the WHO CONTAMINATION: Letting the coronavirus spread throughout the population for collective immunity is not an option If you are strong do not fear the second wave, but as you say, “Well at least after that, we will all infected and immunized collectively,” your Monday night might be more depressing than expected: WHO ruled Monday unthinkable to let Covid-19 circulate freely in society so that the population has access, as some have suggested, to collective immunity.
“Never in the history of public health has herd immunity been used as a strategy to respond to an epidemic, let alone a pandemic.
Seroprevalence surveys suggest that in most countries, less than 10% of the population has been infected ”, detailed Tedros Adhanom Ghebreyesus.
The concept of collective immunity valid only in the event of vaccination He also explained that the world did not know enough about the immunity enjoyed by people who contracted Covid-19, pointing out that some individuals have been newly infected.
“Most people infected with the virus develop an immune response during the first few weeks, but we don’t know if this response is strong or long-lasting, or if it differs from person to person,” he said.
He stressed that the concept of collective immunity is used in vaccination campaigns and he recalled that for smallpox it is necessary that 95% of the population be vaccinated so that the remaining 5% are protected.
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 Can herd immunity help stop coronavirus?
What we know now - CNET Editions Editions Search Go Hi, Settings Join / Sign In Can herd immunity help stop coronavirus?
What we know now How herd immunity happens and what that means for the novel coronavirus.
July 26, 2020 6:15 a.m. PT Listen - 09:15 Herd immunity occurs when the vast majority of people in a geographic region are immune to a disease, eventually stopping its spread.
Getty Images For the most up-to-date news and information about the coronavirus pandemic, visit the .
, the term "herd immunity" has been tossed around as one solution to the devastating virus since December 2019.
The term explains the situation in which a high percentage of people in a given community (a city, state or entire country) is immune to a disease, either through or because those people have been and their have built antibodies to protect them from it.
People who tout it as the best , the virus that causes , are correct in their thinking -- it's the best way to prevent contagious diseases from circulating throughout a population because it slows down or eliminates the from person to person.
The problem with herd immunity and the novel is that the world is nowhere close to having widespread resistance to COVID-19, and is still a long way from developing it -- even after six months of battling out this pandemic.
to of a population must have immunity to a disease for it to stop spreading.
Even as of July 2020, as cases have (and ), herd immunity isn't anywhere close.
For reference, the US population is about 330 million -- 90% of that is 297 million.
One factor standing in the way of reaching that 90% is that large-scale coronavirus research has suggested that , which could mean that herd immunity is farther away than anyone thinks.
Let's explore what herd immunity looks like, what it means for COVID-19 and how the world can get there, explained by Dr. Jane Orient, executive director of the ; , a Yale Medicine infectious disease specialist; and the Centers for Disease Control and Prevention.
Now playing: Watch this: Vaccines, antibody tests, treatments: The science of... 6:02 What is herd immunity?
Orient tells CNET that herd immunity is what slows and eventually stops outbreaks and epidemics -- this occurs only "when the pathogenic organism runs out of susceptible victims because of isolation, quarantine or immunity of exposed persons."
Orient -- who says she really prefers the term "population immunity" because "we are not livestock" -- emphatically points out that "If it weren't for population immunity … we'd all die like the Martians in The War of the Worlds."
In the movie, the Martians who travel to Earth all die from an Earth-borne bacteria that the Martians' immune systems couldn't handle.
Vinetz explains that a good example of herd immunity is the measles.
"The idea is that if we have herd immunity, it means that we reduce the transmission of a disease within a population," Vinetz says.
The idea, Vinetz concludes, is to remove the possibility of sustained transmission.
While "active immunity," or immunity a person builds in response to actually contracting a disease, is most effective and long-lasting, with SARS-CoV-2 in an attempt to build immunity.
Fighting coronavirus: COVID-19 tests, vaccine research, masks, ventilators and more How vaccines promote herd immunity The purpose of vaccines, Orient says, is "to expose people to something that induces immunity without making them very sick," explaining that vaccines are either tiny doses of a pathogen, a dead microorganism or one that is similar but weaker.
"You need upwards of 70% of protective immunity in a population to prevent large scale propagation," Vinetz explains, and that often requires immunization, particularly in regard to diseases that have been almost eradicated in the US.
Vinetz again points to measles as the best example.
"But if we let ourselves become vulnerable by not vaccinating, a case that could touch off an outbreak of some disease that is currently under control is just a plane ride away."
Vaccines have been successful in creating herd immunity to several infectious diseases.
Getty Images Only one disease -- variola virus, better known as -- has been completely eradicated.
"For milder diseases, not necessarily so."
Vaccines can have adverse effects for some people, too, and immunity wanes over time, so the importance of vaccination depends on a number of factors, including severity and prevalence of the disease, vaccine safety and individual patient factors, Orient explains.
"Everything is a trade-off," she reminds us.
mosquito control), or cure of the sick before disease can be transmitted."
Why we need herd immunity If there is no herd immunity, people will continue to contract and spread diseases, and, unfortunately, people will continue to die from these diseases.
The CDC defines herd immunity, or , as "a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely."
"Even individuals not vaccinated (such as newborns and those with chronic illnesses)," the CDC continues in its definition of herd immunity, "are offered some protection because the disease has little opportunity to spread within the community."
Coronavirus in pictures: Scenes from around the world SARS-CoV-2, the virus that causes COVID-19, is a hauntingly relevant example.
This virus is new to humans, so no one has immunity, naturally or by vaccination.
Because no one has immunity, and the virus is contagious, it .
What will it take to have coronavirus herd immunity?
There are two ways to produce herd immunity against a disease: develop and administer a safe and effective vaccination, or wait for the disease to make it around through a population.
Without a vaccine, shelter-in-place and -- or the polarizing issue of -- are the only ways to slow the spread while we wait for a vaccine to be developed.
Vinetz figures that the US is nowhere near the point of herd immunity to the novel coronavirus: "If we have 330 million people in the States and 1% are infected, that's 3.3 million people and that still means that 99% of the US population remains susceptible."
If you take Vinetz's estimation that at least 70% of a population must be immune to a disease to produce herd immunity, that means at least 231 million people in the US must contract and recover from the disease.
The actual number of COVID-19 cases in the US had just barely surpassed 1% of the population as of July 22, 2020 (you can , which is updated continuously).
"It doesn't require Einstein to figure out that we are nowhere close to herd immunity," Vinetz says starkly.
However, too many important factors remain unknown to simply allow the virus to continue its rampage without intervention: .
or did not feel sick enough to get tested.
See the emptiness as coronavirus closes landmarks, stadiums, amusement parks When will we have coronavirus herd immunity?
We've also now seen that striving for herd immunity doesn't work in practice: Sweden, one country that many people looked to as an example because of its leniency during the pandemic, is because the death toll is "unnerving."
Whether we will see herd immunity to SARS-CoV-2 in the future depends heavily on a number of factors -- particularly, Orient says, "whether we allow people to move around."
"If we lock everybody into solitary confinement, they won't get immune, unless and until there is an effective vaccine," she explains.
"For some diseases, like the common cold (coronaviruses are one cause) there isn't much herd immunity because the virus changes or the vaccine just doesn't work, like ."
When asked about localized herd immunity, or herd immunity within specific regions with high numbers of coronavirus cases (such as New York and California), Vinetz says the concept doesn't really matter if people are allowed to roam around.
"We're such a mobile society," he says, so if are relaxed or removed, "if people start getting on buses and planes and trains and visiting other areas," localized herd immunity means nothing.
Vinetz says he expects to see "continual rolling waves of [COVID-19] infection unless we intervene somehow," squashing the idea that there will be a in the fall of 2020 simply because it likely will not have died down or disappeared by that point.
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What is an 'intelligent lockdown'?
The Dutch are among the few who began by openly embracing the contentious idea of group or herd immunity.
It's an approach characterised by one Dutch global health expert as cold and calculated.
Cities may be quieter, but children still clamber on climbing frames and teenagers cycle side-by-side.
How Dutch went beyond UK on herd immunity When the UK's chief scientific adviser revealed a plan to develop a broad immunity across the population, within days researchers revealed it could claim a quarter of a million lives, and the UK changed course.
Allowing a deadly virus to spread through society to create a level of immunity implicitly means accepting people will die.
In a televised speech to the nation on 16 March, .
"We can delay the spread of the virus and at the same time build up population immunity in a controlled manner," he said.
Dutch government The bigger the group that acquires immunity, the smaller the chance that the virus can make the leap to vulnerable older people or people with underlying health issues Mark Rutte Dutch Prime Minister, 16 March 2020 "We have to realise that it can take months or even longer to build up group immunity and during that time we need to shield people at greater risk as much as possible."
For Dr Van de Pas it's a cold and calculated Dutch approach, that can perhaps only work in an individualistic society used to a non-interventionist medical culture, from cradle to grave.
While herd immunity, modified as it is, may eventually dampen the effects of the epidemic, it has to be accepted by a substantial part of the population.
The worry is that the Dutch approach may be based more on aspiration than actual intelligence, and that the Netherlands' "intelligent lockdown" does not make the country immune.

 Sweden is beating coronavirus because of widespread immunity after refusing to lock down, country claims The Sun, A News UK Company Close Your Sun Editions News Corp is a network of leading companies in the worlds of diversified media, news, education, and information services.
Follow The Sun The Sun News Corp Services TOP All Football ‘WE’RE DOING FINE’ Sweden is beating coronavirus because of widespread immunity after refusing to lock down, country claims SWEDEN'S health experts have claimed they are beating coronavirus because of immunity after refusing to go into lockdown.
That is more than double of France - recording 349 cases per 100,000.
However, Dr Tegnell claims the higher level of cases indicates a form of immunity among the population by people carrying antibodies for Covid-19.
Dr Tegnell told the Unherd website last month: "What we are seeing now in Sweden is a rapid decline in the number of cases, and of course some sort of immunity must be responsible for that since nothing else has changed."
A study published last week by the Karolinska Institute in Stockholm people who test negative for antibodies may still have a high level of immunity.
Dr Tegnell said: "I think it is likely that such outbreaks will be easier to control in Sweden because there is immunity among the population."
Professor Marcus Buggert, an immunologist at the institute, said: "T-cells are a type of white blood cells that are specialised in recognising virus-infected cells.
"Our results indicate that roughly twice as many people have developed T-cell immunity compared with those who we can detect antibodies in."
Earlier this month, the pointed out that Sweden's antibody rate is fairly similar to the UK's.

 Herd Immunity: What It Means for COVID-19 Subscribe What Is Herd Immunity and Could It Help Prevent COVID-19?
Medically reviewed by — Written by on April 2, 2020 You’ve probably heard the term “herd immunity” used in relation to the .
Some leaders — for example, Boris Johnson, the prime minister of the United Kingdom — suggested it might be a good way to stop or control the spread of the new coronavirus, which causes COVID-19.
Herd immunity is also called community immunity and herd or group protection.
Herd immunity happens when so many people in a community become to an infectious disease that it stops the disease from spreading.
This can happen in two ways: against the disease to achieve immunity.
Herd immunity can work against the spread of some diseases.
There are several reasons why it often works.
There are also many reasons why herd immunity won’t yet work to stop or slow the spread of or COVID-19, the disease caused by an infection of the new coronavirus.
When a large percentage of the population becomes immune to a disease, the spread of that disease slows down or stops.
This chain is broken when most people don’t get or transmit the infection.
This helps protect people who aren’t vaccinated or who have low functioning immune systems and may develop an infection more easily, such as: systems For some diseases, herd immunity can go into effect when of the people in a population become immune to the disease, such as through vaccination.
But in most cases, 80 to 95 percent of the population must be immune to the disease to stop its spread.
For example, must have the vaccination for herd immunity to go into effect and stop the disease.
This means that if a child gets measles, everyone else in this population around them will most likely have been vaccinated, already have formed antibodies, and be immune to the disease to prevent it from spreading further.
The goal of herd immunity is to prevent others from catching or spreading an infectious disease like measles.
However, if there are more unvaccinated people around the child with measles, the disease could spread more easily because there is no herd immunity.
To visualize this, picture someone without immunity as a red dot surrounded by yellow immune dots.
If the red dot can’t connect to any other red dots, there is herd immunity.
The percentage of people that must have immunity to safely slow or stop an infectious disease is called the “herd immunity threshold.” Natural immunity occurs when you become immune to a specific disease after contracting it.
This triggers your immune system to make antibodies against the germ causing the infection inside of you.
If you contract it again, the antibodies that dealt with the germ before can attack it before it spreads and makes you ill. For example, if you had chickenpox as a child, you most likely won’t get it again, even if you’re around someone with it.
Natural immunity can help create herd immunity, but it doesn’t work as well as vaccinations.
There are several reasons for this: Herd immunity does work for some illnesses.
People in Norway successfully developed at least partial herd immunity to the H1N1 virus ( ) through vaccinations and natural immunity.
Similarly, in Norway, influenza was projected to cause fewer deaths in 2010 and 2011 because more of the population was immune to it.
Herd immunity can help stop the spread of illness, such as swine flu, and other pandemics within an entire country.
But it can change without anyone knowing.
Also, it doesn’t always guarantee protection against any disease.
For most healthy people, herd immunity isn’t a good alternative to getting vaccinated.
Not every illness that has a vaccine can be stopped by herd immunity.
For example, you can contract from bacteria in your environment.
You don’t contract it from someone else, so herd immunity doesn’t work for this infection.
Getting the vaccine is the only protection.
You can help build herd immunity to certain diseases in your community by making sure you and your family have up-to-date vaccinations.
Herd immunity may not always protect every individual in the community, but it could help prevent widespread disease.
Social distancing and frequent handwashing are currently the only ways to help prevent you and those around you from contracting and potentially spreading SARS-CoV-2, the virus that causes COVID-19.
There are several reasons why herd immunity isn’t the answer to stopping the spread of the new coronavirus: for SARS-CoV-2.
Vaccinations are the safest way to practice herd immunity in a population.
Scientists are currently working on a vaccine for SARS-CoV-2.
If we have a vaccine, we may be able to develop herd immunity against this virus in the future.
This would mean getting the SARS-CoV-2 in specific doses and making sure the majority of the world’s population is vaccinated.
Almost all healthy adults, teens, and older children would need to be vaccinated to provide herd immunity for people who can’t get the vaccine or who are too ill to become naturally immune to it.
If you’re vaccinated and build immunity against SARS-CoV-2, you most likely wouldn’t contract the virus or transmit it.
Herd immunity is community or group protection that happens when a critical number of the population is immune to a certain disease.
It can help stop or slow the spread of an infectious disease like measles or swine flu.
The safest way to get immunity is through vaccination.
You can also get natural immunity by contracting the illness and building an immune response to it.
Herd immunity isn’t the answer to stopping the spread of SARS-CoV-2, the new coronavirus that causes COVID-19.
Once a vaccine is developed for this virus, establishing herd immunity is one way to help protect people in the community who are vulnerable or have low functioning immune systems.

The Sun, A News UK Company Close Your Sun Editions News Corp is a network of leading companies in the worlds of diversified media, news, education, and information services.
Follow The Sun The Sun News Corp Services TOP All Football TENDING THE HERD What is herd immunity?
HERD immunity seems to be the buzz world in academic and scientific circles as the world hopes for an end to the coronavirus pandemic.
Here's the latest after the World Health Organisation cautioned the world has needed for herd protection.
⚠️ Read our for the latest news & updates The UK has not used herd immunity as an approach Credit: 2020 Pete Maclaine / i-Images What is herd immunity?
Herd immunity refers to where enough people in a population have immunity to an infection to be able to effectively stop that disease from spreading.
Herd immunity is typically best achieved with .
While the term herd immunity is widely used, it can carry a variety of meanings.
The NHS outlines “herd immunity” as when enough people in a community are vaccinated against a disease, making it more difficult for it to spread to susceptible individuals who have not yet been or cannot be vaccinated.
Academics from the London School of Hygiene and Tropical Medicine wrote that while some use the term to describe the proportion of individuals in a community who are immune to a condition, others use it in reference to “a particular threshold proportion of immune individuals that should lead to a decline in incidence of infection”.
They added: “A common implication of the term is that the risk of infection among susceptible individuals in a population is reduced by the presence and proximity of immune individuals.” 2 Herd immunity is typically best achieved with vaccination Credit: Reuters How does it work?
The Vaccine Knowledge Project at Oxford University uses an analogy of a person being infected by measles.
The organisation states: “If someone with measles is surrounded by people who are vaccinated against measles, the disease cannot easily be passed on to anyone, and it will quickly disappear again.
“This is called ‘herd immunity’, ‘community immunity’ or ‘herd protection’, and it gives protection to vulnerable people such as newborn babies, elderly people and those who are too sick to be vaccinated.” However, the organisation stresses that herd immunity “only works” if the majority of a population has been vaccinated against a condition, adding that it “does not protect against all vaccine-preventable diseases”.
“Unlike vaccination, herd immunity does not give a high level of individual protection, and so it is not a good alternative to getting vaccinated,” the Vaccine Knowledge Project says.
Professor of infectious disease epidemiology at the University of Edinburgh, Professor Mark Woolhouse, told that the concept of herd immunity is “the basis of all vaccination programmes”.
He explained: “If you’ve been exposed to any infection, enough people have already been exposed to it, have developed antibodies and they’re immune to it, you can have natural herd immunity, and that particular virus will not be able to cause an epidemic in the population.
“It doesn’t mean it won’t be able to spread as there’ll still be some susceptible people, but it won’t take off and cause an epidemic.” The proportion of people needed that are immune to the disease in order to prevent an epidemic varies and depends on how infectious the disease is.
Using the measles analogy, Professor Paul Hunter, a professor in medicine at the University of East Anglia, explained: “With something like measles that is very infectious, you need something like 90 per cent of people immune, but with other infections you can get away with much less.” However, Vaccine Knowledge project manager Tonia Thomas warned that the prospect of developing immunity to a condition through infection, rather than through vaccination, could be harmful, as people may “risk developing complications from the disease”.
“Vaccines are a safer way to develop immunity, without the risks associated with the disease itself,” she said.
WHO has also said that while many people around the world have developed immunity to seasonal flu strains, the same cannot be said for the .
WHO said: “Covid-19 is a new virus to which no one has immunity.” While antibodies may be detected among people who have previously tested positive for the virus, “there is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection", the organisation stressed.
“One thing we know about these coronaviruses is that people can get reinfected fairly often,” said Professor Stuart Neil, co-author of the study.
“What that must mean is that the protective immunity people generate doesn’t last very long.
It looks like Sars-Cov-2, the virus that causes Covid-19, might be falling into that pattern as well.” And in August, scientists at Hong Kong University claimed they had discovered the stating that the man had been infected twice by different versions of the coronavirus months apart.
Has it been used for coronavirus in the UK?
On March 15, a statement released by Health Secretary on the government’s website denied achieving herd immunity was its intention.
“We have a plan, based on the expertise of world-leading scientists.
Herd immunity is not a part of it,” the statement read.
“That is a scientific concept, not a goal or a strategy.
Our goal is to protect life from this virus, our strategy is to protect the most vulnerable and protect the NHS through contain, delay, research and mitigate.” 2 Herd immunity refers to where enough people in a population have immunity to an infection to be able to effectively stop that disease from spreading Credit: Getty Images - Getty What countries have used herd immunity?
opted to use herd immunity as a strategy to beat coronavirus.
No businesses were forced to shut down, as wanted to limit the impact on its economy.
Director of Swedish public health Johan Carlson, who was a leading figure behind the herd immunity policy, has said it appeared now to have worked.
Swedish health experts have because of immunity after refusing to go into lockdown.
He told reporters that we should not live in hope of achieving natural .
Dr Ryan said: "As a global population, we are nowhere close to the levels of immunity required to stop this disease transmitting.
"This is not a solution and not a solution we should be looking to."
He said: "We don't want to be wrong.
"You want to plan to get high coverage and not get lulled into a dangerously seductive suggestion that (the herd immunity threshold) could be low."
WHO warns world is NOWHERE near coronavirus herd immunity Topics Comments are subject to our community guidelines, which can be viewed .

Professor Kim Sneppen, an expert in the spread of coronavirus at the Niels Bohr Institute in Copenhagen, said that Sweden might have beaten the pandemic.
He told Denmark's Politiken newspaper : 'There is some evidence that the Swedes have built up a degree of immunity to the virus which, along with what else they are doing to stop the spread, is enough to control the disease.
Professor Kim Sneppen, (pictured) an expert in the spread of coronavirus at the Niels Bohr Institute in Copenhagen, said that Sweden might have beaten the pandemic 'Perhaps, the epidemic is over there.'
It is thought that because many younger people have already had coronavirus in Sweden it now has less chance to spread through the population.
Recent studies suggested that an infection rate of 43 per cent may be enough to achieve herd immunity - a figure much lower than the 60 per cent previously cited.
Herd immunity is a situation in which a population of people is protected from a disease because so many of them are unaffected by it - because they've already had it or have been vaccinated - that it cannot spread.
When these have been created once, some of them remain in the body and the body also remembers how to make them again.
Antibodies - alongside T cells - provide long-term protection, or immunity, against an illness.
If nobody is immune to an illness – as was the case at the beginning of the coronavirus outbreak – it can spread like wildfire.
However, if, for example, half of people have developed immunity – from a past infection or a vaccine – there are only half as many people the illness can spread to.
As more and more people become immune the bug finds it harder and harder to spread until its pool of victims becomes so small it can no longer spread at all.
The threshold for herd immunity is different for various illnesses, depending on how contagious they are – for measles, around 95 per cent of people must be vaccinated to it spreading.
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Search with google More This article is more than 3 months old Scientists call for Covid herd immunity strategy for young This article is more than 3 months old Critics describe proposal to isolate vulnerable, disabled and older people as ‘grotesque’ Science editor Tue 6 Oct 2020 19.16 BST Last modified on Wed 7 Oct 2020 04.37 BST The scientists argue that young people, such as self-isolating students at Sheffield Hallam University, pictured, should be allowed to resume normal life.
Photograph: Danny Lawson/PA An international group of scientists has called on governments to overturn their coronavirus strategies and allow young and healthy people to return to normal life while protecting the most vulnerable.
The proposal, drawn up by three researchers but signed by many more, argues for letting the virus spread in low-risk groups in the hope of achieving “herd immunity”, where enough of the population is resistant to the virus to quell the pandemic.
Described as “ ”, after the Massachusetts town where it was drawn up, the plan marks the latest round in a hotly contested debate between scientists who back to the crisis.
In a responding to the declaration, Gregg Gonsalves, an epidemiologist at Yale University, said shutdowns and other interventions were necessary to reduce rates of infection.
With nearly half of the population having some underlying health risk for Covid-19, he said herd immunity strategies were about “culling the herd of the sick and disabled.
It’s grotesque.” Topics Support The Guardian Available for everyone, funded by readers © 2021 Guardian News & Media Limited or its affiliated companies.

Search Herd Immunity: How does it work?
General Public Engagement 26 April 2016 Dr Manish Sadarangani explains how herd immunity works and why vaccinating children is important.
Manish Sadarangani : Herd immunity describes how a population is protected from a disease after vaccination by stopping the germ responsible for the infection being transmitted between people.
By being vaccinated an individual is not only protected from being infected themselves but they then also cannot pass this infection onto other people, where it may cause severe disease.
However, for herd immunity to work a large proportion of the population need to be vaccinated.
Infectious agents (germs) spread between the people in orange, although they do not get severe disease.
This now protects those in yellow as well, who had previously got the infection and possibly the disease.
Although the figure only shows a few people being vaccinated, in reality many people have to be vaccinated for herd immunity to work.
Q: Why is it important that children are vaccinated if they can be protected through herd immunity?
MS: For many diseases children, and in particular young children, are at the highest risk of the disease and also have the most severe illness.
The best way to protect someone against a disease is to vaccinate them directly, rather than rely on ‘indirect’ protection through herd immunity.
If someone who is unvaccinated does meet the germ responsible for that disease they will be completely susceptible.
There will always be some children who cannot be vaccinated for medical reasons – most commonly because they are too young or because they have a problem with their immune system.
It doesn’t take much of a drop in the number of people vaccinated in a population for herd immunity to be less effective and this isn’t then a reliable way of protecting a child.
Q: How many children need to be vaccinated for herd immunity to work?
MS: This varies depending on the germ and how contagious it is.
The more contagious it is then the more people need to be vaccinated for herd immunity to work.
For example, is very contagious.
Before the use of the measles vaccine, every person with measles would infect another 10-15 people and so the disease would spread very quickly.
To achieve herd immunity for measles at least 90-95% of the population need to be vaccinated.
A disease like is less contagious, and 80-85% of the population would need to be vaccinated for herd immunity to work.
Although this is lower it is still a very high proportion, especially given that some people cannot be vaccinated for medical reasons.
Q: Does herd immunity work for all diseases?
Herd immunity only works for diseases that are spread directly between people (i.e.

 Herd immunity and COVID-19 (coronavirus): What you need to know - Mayo Clinic COVID-19: What you need to know ​ Skip to site navigation Skip to Content This content does not have an English version.
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Herd immunity and COVID-19 (coronavirus): What you need to know Understand what's known about herd immunity and what it means for coronavirus disease 2019 ( COVID-19 ).
Curious as to whether herd immunity against the coronavirus disease 2019 ( COVID-19 ) might slow the spread of the disease?
Understand how herd immunity works and what experts are saying about its potential impact on the COVID-19 pandemic.
Why is herd immunity important?
Herd immunity occurs when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely.
As a result, the whole community becomes protected — not just those who are immune.
If the proportion of the population that is immune to the disease is greater than this threshold, the spread of the disease will decline.
This is known as the herd immunity threshold.
What percentage of a community needs to be immune in order to achieve herd immunity?
It's estimated that 94% of the population must be immune to interrupt the chain of transmission.
There are two paths to herd immunity for COVID-19 — vaccines and infection.
Vaccines A vaccine for the virus that causes COVID-19 is an ideal approach to achieving herd immunity.
Vaccines create immunity without causing illness or resulting complications.
Herd immunity makes it possible to protect the population from a disease, including those who can't be vaccinated, such as newborns or those who have compromised immune systems.
Using the concept of herd immunity, vaccines have successfully controlled deadly contagious diseases such as smallpox, polio, diphtheria, rubella and many others.
Reaching herd immunity through vaccination sometimes has drawbacks, though.
People who object to vaccines often live in the same neighborhoods or attend the same religious services or schools.
If the proportion of vaccinated people in a community falls below the herd immunity threshold, exposure to a contagious disease could result in the disease quickly spreading.
Measles has recently resurged in several parts of the world with relatively low vaccination rates, including the United States.
Opposition to vaccines can pose a real challenge to herd immunity.
Natural infection Herd immunity can also be reached when a sufficient number of people in the population have recovered from a disease and have developed antibodies against future infection.
During the 2009-10 flu season, H1N1 caused the respiratory infection in humans that was commonly referred to as swine flu.
However, there are some major problems with relying on community infection to create herd immunity to the virus that causes COVID-19 .
First, it isn't yet clear if infection with the COVID-19 virus makes a person immune to future infection.
Further research is needed to determine the protective effect of antibodies to the virus in those who have been infected.
Even if infection with the COVID-19 virus creates long-lasting immunity, a large number of people would have to become infected to reach the herd immunity threshold.
Experts estimate that in the U.S., 70% of the population — more than 200 million people — would have to recover from COVID-19 to halt the epidemic.

 Natural herd immunity can’t stop the COVID-19 pandemic.
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All rights reserved Painting by Ernes Board, DEA Picture Library, Getty Images Read Caption The history of herd immunity can explain why we need an effective vaccine to beat COVID-19.
Above: Edward Jenner (1749-1823) performs his first vaccination against smallpox on James Phipps, a boy of eight, May 14, 1796, oil on canvas.
Painting by Ernes Board, DEA Picture Library, Getty Images A 'herd mentality' can’t stop the COVID-19 pandemic.
Debates over herd immunity and natural infection arise with every outbreak.
Effective vaccination always wins.
10 Minute Read By PUBLISHED October 2, 2020 Early disease fighters, such as Edward Jenner, Louis Pasteur, and William Farr, suspected if enough people were vaccinated, it could eradicate a disease.
At the dawn of the 20th century, veterinarians more interested in livestock than people seized on the idea and coined the term “herd immunity.” By the 1920s, clever studies with hundreds of thousands of mice vaulted the idea into the mainstream, stirring optimism that making a fraction of a population immune could forestall a devastating outbreak.
But even the trailblazers researching herd immunity were mystified by how to deploy it in practice.
And now it is part of the debate as the COVID-19 pandemic continues to flourish around much of the world.
Some wonder if herd immunity created as people are naturally infected with SARS-CoV-2 coronavirus would be enough to restore society to working order.
For evidence, such as New York City, where approximately 20 percent of the residents have been infected and the caseload has been low and steady for months.
But based on simple math, past experiences with outbreaks, and emerging evidence from the ongoing pandemic, this claim is a fantasy.
“If we had reached sufficient herd immunity in New York, you would expect incidents to continue going down, not to be holding steady,” says , an epidemiologist at the Yale School of Public Health who specializes in the mathematical modeling of how diseases spread.
A vaccine with 50-percent efficacy could spare hundreds of thousands from hospitalizations, chronic health issues, and death—but it couldn’t hit the herd immunity threshold on its own even if everyone took it.
The model assumes an and a basic reproduction number of 3.0.
It also assumes that immunity develops after infection, so does not allow for reinfection, and that a vaccine is the sole intervention among the masses.
SOURCE: PHICOR The reality is that most of the world— —remains susceptible to infection by the coronavirus virus, despite the global toll so far.
Banking on natural infection to control the outbreak would lead to months, if not years, of a dismaying cycle in which cases subside and then surge.
Even if such community-mediated protection were established, it would be constantly eroded by the birth of children and the real possibility that immunity in those previously infected would wane.
Only two infectious diseases have ever been eradicated: the human scourge of smallpox and the cattle-borne germ rinderpest.
All other known afflictions—including such Old World pestilences as , , and —have either been managed through human intervention or remain uncontrolled.
“It's very unlikely that we're going to see elimination of COVID-19 altogether from the population simply through the buildup of natural immunity,” says Pitzer.
But if we add a highly effective vaccine on top of that, Pitzer says, “then it is theoretically possible that we could eliminate the virus” or at least control it.
A crucial step will be communicating how good the vaccine needs to be to stop transmission.
While major health agencies, including the and the , say a COVID-19 vaccine should be at least 50-percent effective to be approved, this benchmark would actually be too low to establish protective herd immunity.
“It doesn't mean that a vaccine that's below this certain threshold will not be useful,” says , professor and executive director of Public Health Computational and Operations Research (PHICOR) at the City University of New York School of Public Health.
“But if you want to be in a situation where you don't have to do social distancing and these other things anymore, then the vaccine really needs to be over 80 percent efficacy.” What we mean when we talk about herd immunity Herd immunity’s prominence in fighting epidemics can trace its origins to the 1920s and the University of Manchester in England.
Inside a lab there, about 15,000 mice per year scurried through what looked like moon bases in miniature.
Members of one city would be exposed to lethal bacteria, while those in a separate city would receive doses of a vaccine along with the dangerous germ.
The duo’s findings— —demonstrated that immunity in a portion of a population could slow an outbreak and protect otherwise susceptible individuals.
“They called it ,” says , a professor of communicable disease epidemiology at the London School of Hygiene & Tropical Medicine, who has about the origins of herd immunity.
Topley and Wilson—along with some help from —helped popularize the idea, particularly through that’s still used by students to this day.
Yet when most people discuss herd immunity today, they’re really talking about what’s known as the “herd threshold theorem.” It’s what scientists are referencing when they say 75 percent of the population needs to be immune against COVID-19 to stop disease transmission, and it’s surprisingly simple to calculate.
Say a germ lands in foreign world, where an entire population is susceptible.
He sneezed in four faces, but three of those individuals were immune,” Fine says.
Three out of four is three-quarters, meaning a 75-percent threshold is needed to reach herd immunity.
Different viruses have their own reproduction numbers, so each has its own herd immunity threshold.
The mass vaccination program , but nearly a decade later, the disease remained endemic in much of Africa, Asia, and South America, with tens of thousands of cases still reported each year.
The virus kept finding hideouts—both in rural areas and high-density cities where it could fester—and ultimately threaten disease-free areas given that the vaccine’s immunity only lasted five years.
The tide turned on December 4, 1966, when a missionary in the southeastern Nigerian region of Ogoja radioed Foege to warn of a new possible outbreak.
That’s a huge advantage—especially when an epidemic nears elimination and mass vaccination becomes less cost effective.
By 1971, an epidemiologist named John Fox herd immunity models that would better incorporate heterogeneity, and decades later it is still standard practice for public health researchers.
The practice is similar to how firefighters clear trees, shrubs, and other flammable debris to encircle a raging wildfire, and it explains why health care workers, first responders, and people in hot spots such as jails .
Stopping Pandemics: An exclusive National Geographic event with Dr. Fauci & other experts National Geographic's exclusive conversation with Dr. Anthony Fauci, Washington, D.C. Mayor Muriel Bowser, and experts from National Geographic and ABC News explores why the COVID-19 pandemic is wreaking havoc on communities and the lessons we can learn from health pandemics throughout history, August 13, 2020.
Our future with COVID-19 depends on us On August 14, , a mathematician at Stockholm University in Sweden, and two other scientists released a model in that estimates how social activity might influence the herd immunity threshold.
They started with the valid assumption that millennials and Gen Z mix more than older people, and so will more readily spread the virus.
Britton’s team landed on a herd threshold of 43 percent—much lower than the 60 to 75 percent you get using the classic equation.
“We don't claim that the number from our model applies in reality,” Britton cautions, adding that the model merely shows the degree to which disease-induced immunity can play a role.
“We don't want our paper to have the consequence that people feel relaxed and say, Let's skip restrictions and wait for herd immunity.” Another limitation of heterogeneity modeling, Columbia University’s Shaman says, is that no one really knows how germs spread among people on the street, so it’s difficult to tell what these reduced thresholds mean for real life.
“That completely changes the landscape.” Moreover, recent studies of explosive COVID-19 outbreaks in two different regions suggest the classic herd theorem might be valid.
In Qatar, the herd immunity threshold appears to have been achieved in about 10 working-class communities.
“So 60 percent of the population of Qatar is migrant workers.
But raises questions about whether the city truly achieved community protection—or worse, if .
If the latter, the virus will bounce back even if places reach the herd immunity threshold through natural routes.
This vulnerability would be reinforced by children, who are born without immune defenses and thus are susceptible to catching and spreading the disease.
Another concern for waning immunity would be frequent reinfections that result in severe symptoms, Shaman says.
“This would suggest we're not going to be done with this any time soon, and that prior exposure doesn't lessen your chance of winding up in the hospital,” he says.
Though has been reported worldwide, there’s no evidence yet this is happening on a broad scale.
If society wants to overcome these bleak possibilities and return to life without social distancing and mask wearing, it needs a vaccine that provides a sufficient amount of what’s known as sterilizing immunity, meaning the drug blocks coronavirus transmission.
“I would say the sweet spot is 80 percent,” says CUNY’s Lee, who co-authored about efficacy goals for the COVID-19 vaccine.
“We have to make it clear to everyone that the first vaccine to reach the market may not achieve those efficacy levels,” Lee says.
“It's not that easy to get an efficacy that high for a respiratory virus.” That’s because current guidance says vaccine frontrunners can be approved even if they only provide “functional immunity,” which mainly confers protection against the symptoms of the disease.
The ongoing COVID-19 vaccine trials are not designed to estimate the impact the vaccine candidates would have on transmission, write the authors of the National Academy of Medicine report, adding that we may not learn this impact until well after an FDA approval.

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Thursday 8 October 2020 09:00, UK Image: The declaration makes several suggestions to achieve herd immunity Top scientists are calling for a herd immunity approach to the coronavirus pandemic by allowing people who are less vulnerable to the effects of the disease to return to normal life.
The so-called Great Barrington declaration, signed by leading experts from the universities of Oxford, Nottingham, Edinburgh, Exeter, Cambridge, Sussex and York, suggests herd immunity as a way forward.
The declaration states: "The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up immunity to through natural infection, while better protecting those who are at highest risk.
"We call this focused protection."
More from Covid-19 But other scientists have described the idea of "focused protection" as "wishful thinking".
Dr Rupert Beale, group leader of the cell biology of infection laboratory at the Francis Crick Institute, says herd immunity is "very unlikely" before a vaccine is found.
He said: "This declaration prioritises just one aspect of a sensible strategy - protecting the vulnerable - and suggests we can safely build up 'herd immunity' in the rest of the population.
It is not possible to fully identify vulnerable individuals, and it is not possible to fully isolate them.
"Furthermore, we know that immunity to coronaviruses wanes over time, and re-infection is possible - so lasting protection of vulnerable individuals by establishing 'herd immunity' is very unlikely to be achieved in the absence of a vaccine."
Please use Chrome browser for a more accessible video player Hundreds of musicians give protest performance The declaration follows comments by the leader of the NHS in England, Sir Simon Stevens, who said that asking all over-65s to shield would be "age-based apartheid".

Over half a century after the Cork epidemic, the British government and its medical advisers find themselves in something of the same dilemma.
They clearly considered “herd immunity”, and going down the same road as Sweden, but they jumped away from the idea when it met with a fiercely negative public reaction.
"Our aim," said the chief scientific officer Sir Patrick Valance on 13 March, ten day before lockdown, “is to build up some degree of herd immunity whilst protecting the most vulnerable".
Read more Of course, protecting the most vulnerable turned out to be exactly what the government did not do as mass deaths in the care homes demonstrated.
Countries around the world were likewise soon denying that they were pursuing “herd immunity” as the phrase became a synonym for state-sponsored euthanasia.
Leaving aside the victims in the care homes, critics pointed out that, in addition to those that died, many would be permanently disabled, nor was there in any case, any guarantee that mass infection would confer long term immunity.
The dynamics of epidemics, their lethal ebbs and flows, are unpredictable and complicated involving more than a fixed proportion of people getting the illness.
Yet six months from “herd immunity” being pilloried worldwide as the equivalent of poisoning the wells, Britain may covertly or by default may be adopting just such a policy.
The reason for this creeping volte-face is that while “herd immunity” may or may not be achievable, the alternative policy of lockdown looks more and more like a bad bargain, bringing economic devastation in return for a temporary retreat of the epidemic.
In reality, it has been in “panic mode,” and thanks to its bumbling incompetence, there is plenty to panic about.
More about 1 /1 Britain will seek 'herd immunity' covertly or by default Britain will seek 'herd immunity' covertly or by default Boris Johnson Getty Images Comments Share your thoughts and debate the big issues ✕ About The Independent commenting Independent Premium Comments can be posted by members of our membership scheme, Independent Premium.
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 Coronavirus UK: What is the secret behind herd immunity?
If an Edinburgh University study is to be believed, the most effective way to cut the Covid death toll might be by letting people spread the virus to build up 'herd immunity'.
But just what does that entail?
JOHN NAISH explains… What is herd immunity?
Herd immunity occurs when a large proportion of a population – the herd – is immune to a virus, making it unlikely to spread.
This view was bolstered by the Edinburgh study.
The Edinburgh study examined lockdown-style scenarios and found that while lockdown might protect hospitals, they could also prolong the pandemic and prevent the build-up of herd immunity.
Pictured: The green and purple lines represent deaths that could occur during a second wave, while the black line suggests deaths would have rocketed during the first wave but stayed low throughout the rest of the year if the country didn't go into lockdown How cases and deaths would look if the UK only isolated entire households of Covid-19-positive people and made over-70s lockdown.
Graphs on the left show how younger people would have picked up the virus much more easily and built up some herd immunity.
It would also cause less deaths, shown right, according to the researchers How many must catch the virus?
Experts disagree on how many people it would take to reach 'herd immunity' with Covid.
Kate Bingham, of the Government's vaccine taskforce, said 50 per cent of the population is all it would take, but World Health Organisation chief scientist Soumya Swaminathan says at least 70 per cent.
Other more infectious viruses such as measles require rates of up to 90 per cent.
RELATED ARTICLES Share this article Share Why wasn't herd immunity pursued?
Initially it was, with the Government's chief scientific adviser Sir Patrick Vallance saying on March 12 that 'we need to have immunity to protect ourselves in the future'.
But after Imperial College's Professor Neil Ferguson published a paper warning that 500,000 Britons could die without a national lockdown, the Government was terrified into abandoning its initial plan.
The Government's chief scientific adviser Sir Patrick Vallance said on March 12 (pictured that day) that 'we need to have immunity to protect ourselves in the future' Why are there still doubts?
The truth is that no one is sure how to abandon restrictions while also shielding vulnerable people, as the continuing number of deaths in care homes even after lockdown would appear to show.
There are also concerns that herd immunity may not last for ever, or even beyond a few months.
How close are we to herd immunity?
But figures from random antibody testing last month suggests the actual number could be as low as 7 per cent.
Oxford University's Professor Sunetra Gupta – the author of the Barrington letter – published a study in May claiming coronavirus may have already infected half of the UK population Advertisement Share or comment on this article: Coronavirus UK: What is the secret behind herd immunity?
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 Covid scientist infects himself with virus TWICE to study antibodies & says the hopes for herd immunity are 'overblown' The Sun, A News UK Company Close Your Sun Editions News Corp is a network of leading companies in the worlds of diversified media, news, education, and information services.
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Covid scientist infects himself with virus TWICE to study antibodies & says the hopes for herd immunity are ‘overblown’ A COVID scientist infected himself with the virus TWICE to study antibodies - and has concluded that the hopes for herd immunity are overblown.
Dr Alexander Chepurnov, 69, caught Covid-19 for the first time in February while skiing in France - but he reinfected himself to test if he still had antibodies.
⚠️ Read our for the latest news & updates 3 Dr Alexander Chepurnov caught the virus twice - leading him to the conclusion that herd immunity is overblown Credit: The Siberian Times 3 The scientist purposely infected himself with coronavirus for the second time Credit: The Siberian Times After returning home to Siberia when he first caught the killer virus, Dr Chepurnov and his team at the Institute of Clinical and Experimental Medicine launched a study into Covid antibodies.
He found that the antibodies decreased rapidly, reporting: "By the end of the third month from the moment I felt sick, the antibodies were no longer detected."
To further the study, Dr Chepurnov then purposely reinfected himself with coronavirus to see if he had any immunity.
He deliberately exposed himself to patients who were positive with the virus while wearing no protection.
"After two weeks it was no longer detected in the nasopharyngeal or in other samples."
After completing his studies, the scientist concluded that the hope of herd immunity is overblown and futile.
Immunity via vaccine or transmission may only work as a temporary block of the virus, according to the findings.
He said: "We need a vaccine that can be used multiple times, a recombinant vaccine will not suit.
"Once injected with an adenoviral vector-based vaccine, we won't be able to repeat it because the immunity against the adenoviral carrier will keep interfering."
This comes as Vladimir Putin boasted that a second Covid vaccine had been perfected by Russian boffins - and that a third is in the pipeline.
Herd immunity refers to where enough people in a population have immunity to an infection to be able to effectively stop that disease from spreading.
Herd immunity is typically best achieved with .
While the term herd immunity is widely used, it can carry a variety of meanings.
The NHS outlines “herd immunity” as when enough people in a community are vaccinated against a disease, making it more difficult for it to spread to susceptible individuals who have not yet been or cannot be vaccinated.
Meanwhile, in the UK, - and may never reach natural levels of protection.
Scientists at Imperial College London said immunity is “waning” and noted a 26 per cent drop in positive antibody tests in three months.
In a briefing with journalists, Professor Helen Ward, who worked on the study, said their findings suggest the UK is a "long way" from reaching herd immunity.
"So I think we are a long, long way from any idea that the population will be protected by other people."
3 Herd immunity is unlikely, studies in both Siberia and the UK have said Credit: Vector Topics Comments are subject to our community guidelines, which can be viewed .
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 Life can go back to normal if we make it our common goal to achieve herd immunity Comment Life can go back to normal if we make it our common goal to achieve herd immunity We have a relatively clear picture of who is at risk.
Let's isolate them from harm while the majority of people conduct normal lives 7 October 2020 • 6:38pm When asked how it all began for me, the image that returns is of the 90 year-old street vendor walking back home to her village because lockdown has now forbidden her to sell the few toys on the pavements of Delhi that might occasionally have provided her with a bit of food to eat.
Naturally, an understanding of the dynamics of the spread of SARS-CoV2 (the virus responsible for Covid-19) is of importance in making these difficult decisions.
Mathematical models can be very useful in this regard, and these are all built on the premise that recovery from infection leads to immunity (not necessarily lifelong).
simply describes the ecological process by which immunity accumulates in a community to the detriment of the pathogen; it does not contain any implication or acceptance of culling those who are vulnerable to disease.
To steer a population towards high levels of herd immunity is a sustainable public health goal upon which we have relied to manage a very large catalogue of infectious diseases.
While we remain uncertain about levels of herd immunity that have been attained to SARS-CoV2, we do now have a relatively clear picture of who is vulnerable to severe disease and death upon infection.
that we exploit this feature of Covid-19 to formulate a strategy of Focused Protection, whereby those who are at high risk may be shielded to varying degrees over the period (a maximum of six months) it takes to acquire sufficient herd immunity while the majority of the population conduct normal lives – thereby protecting the whole community from the devastating effects of lockdown.
To answer this, the problem needs at first to be broken down into several parts.
Such inequalities will only be further exacerbated by endless cycles of lockdowns and other restrictions aimed at keeping “case” numbers low.
Once sufficient levels of immunity have built up in the population such that the overall risk remains low (and this may already have happened in many areas), life can go back to normal for everybody.
It should be our common goal to achieve such a state – which will be but cannot rely solely on that route – without causing irreparable damage to those who are vulnerable to other diseases, to the disruption of education and training, to job losses and food insecurity.

You can at any time or find out more by reading our .
Close Main Content There is no ‘scientific divide’ over herd immunity There’s a lot of talk of scientists divided over Covid-19, but when you look at the evidence any so-called divide starts to evaporate By 07 Oct 2020 By Wednesday 7 October 2020 Marco Bottigelli via Getty Images / WIRED On October 4, in a wood-panelled room at an event hosted by a libertarian think tank, three scientists signed a document that they say offers an alternative way of responding to the Covid-19 pandemic.
The signing of this so-called “Great Barrington Declaration” was greeted with clinking champagne glasses before the signatories jetted off to Washington DC on the invite of White House coronavirus advisor Scott Atlas.
Advertisement While the science isn’t particularly convincing, the Great Barrington Declaration has been successful in one respect.
It suggests that scientists fall into two camps: those who are pro-lockdown and those who think we should avoid lockdowns and allow people to become infected, hopefully building up enough herd immunity along the way.
The media has picked up on this narrative of a supposed rift among scientists and has run with it, while simultaneously declaring that no one is talking about it.
So what do the Great Barrington Declaration authors suggest we should be doing?
“Simple hygiene measures, such as hand washing and staying home when sick should be practiced by everyone to reduce the herd immunity threshold.
Schools and universities should be open for in-person teaching.
An AI could write a better book By Amit Katwala This is where things start to feel really wobbly.
For a start, we don’t know enough about Covid-19 immunity to say that having the disease does offer long-term protection.
But even more crucially it’s not clear who exactly the authors mean by “vulnerable”.

Dr Gabriela Gomes, a professor of mathematics and statistics at the University of Strathclyde, made her case against lockdown measures to LBC's Tom Swarbrick.
The professor is one of thousands of scientists and medical experts to have signed a letter calling for the end of lockdown restrictions and a return to a herd immunity strategy.
The 'anti lockdown petition' as it has been called, has been signed by at least 50,000 members of the public, 2,500 scientists and 3,200 medical practitioners so far.
It calls for those who are less vulnerable to the effects of Covid-19 to be allowed to return to normal life, with a herd immunity approach to tackling the Covid-19 pandemic while protecting the most vulnerable.
Dr Gomes told LBC: "Since the beginning of the pandemic we have been acquiring immunity in the population and I've been developing mathematical models to describe that.
"According to our models we are achieving herd immunity right now, which means that an epidemic growing out of control is no longer an expectation.
"So, given that, if we expect the numbers of infections to continue roughly constant for some time and then decline as more immunity is acquired, the rationale for constraining society and lockdowns...is no longer met."
The University of Strathclyde professor also told LBC that the UK would achieve herd immunity when 20% of its population become immune to Covid-19.
The number of new daily coronavirus cases soared past 14,500 on Tuesday - up by 2,000 on the previous day - with 76 new deaths.

 I've crunched the numbers and a herd immunity strategy would lead to a lot of deaths Comment I've crunched the numbers and a herd immunity strategy would lead to a lot of deaths It sounds tempting to get younger people back to normal but shielding the vulnerable would be a monumental undertaking Member of Parliament for Harborough 17 October 2020 • 4:17pm A couple of MPs have recently advocated the ideas It’s the plan that we should end restrictions, get back to normal, and build up herd immunity among working age people, while isolating pensioners and other vulnerable people for six months or so as the virus spreads.
It sounds tempting to get younger people back to normal.
It’s not clear how we’d safely supply them with food as the virus spiked.
How many people would likely die on the way to herd immunity?
Well, although younger people are less likely to die of Covid-19, some do, and the isolation of old and ill people could never be complete: some will have to go to hospital or see carers, or live in care homes, or the young people living with them will not fully isolate and they’ll get it.
About eight per cent of people have had the virus so far (call it 10 per cent to be generous) and on the common assumption that we’ve need to get to 60 per cent for herd immunity to work, we’d need around a further 50 per cent of the younger population to get it.
If we look at mortality rates by age and combine them with the age profile of the UK, then if half of younger people got it and only five per cent of pensioners, that would mean around 90,000 deaths.
What is the track record of the people behind the Declaration?
One of its lead authors predicted in May: “I think that the epidemic has largely come and is on its way out in this country.” She said the decline in cases was “due to the build-up of immunity.” She was wrong.
That’s important because the same reason they wrongly thought it was all over in the summer, is the reason they think it will work now.

 Coronavirus: Did 'herd immunity' change the course of the outbreak?
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Prof Whitty argued that beginning social distancing measures "too early" would risk people becoming tired of them and public compliance waning.
And Sir Patrick began to talk about the concept of herd immunity.
Speaking about the coronavirus he said: "It's not possible to stop everybody getting it and it's also actually not desirable because you want some immunity in the population.
We need immunity to protect ourselves from this in the future."
Mr Johnson reiterated that people should remember to wash their hands.
image copyright Getty Images Sir Patrick was on BBC Radio 4's Today programme.
He said the thinking behind the government's approach was to try to "reduce the peak", and because most people would only get a "mild illness", to "build up some degree of herd immunity… so that more people are immune to this disease and we reduce the transmission".
At the same time, he said, the vulnerable would need to be protected from the virus.
"So that's the flattening of the peak.
You can't stop it, so that you should end up with a broader peak, during which time you would anticipate that more people will get immunity to this and that in itself then becomes a protective part of this process."
He said previous epidemics had shown that measures to strongly suppress the virus risked it bouncing back when they were ended.
Herd immunity "Herd immunity" is a concept describing the point at which a population has developed protection against a disease.
But with any new virus it's impossible to say how long it will take to develop a vaccine, if ever.
The other way is for people to catch the disease and build up some form of immunity.
If exposed to the virus again, it is assumed they have protection.
And if most of the population catches the disease, many thousands might die.
On 13 March, Sir Patrick stated that about 60% of the population would need to become infected for society to have "herd immunity" - effectively some 40 million people in the UK.
"Communities will become immune to it and that's going to be an important part of controlling this longer term," he told Sky News.
A spokesman for the Department of Health and Social Care said Sir Patrick's comments had been misinterpreted.
"Herd immunity is not part of our action plan but is a natural by-product of an epidemic," he said.
That same evening, the Telegraph website published an article by the Health Secretary Matt Hancock.
"We have a plan, based on the expertise of world-leading scientists.
Herd immunity is not a part of it.
That is a scientific concept, not a goal or a strategy."
On Sunday 15 March, the health secretary appeared on the BBC's Andrew Marr and Sky's Sophy Ridge programmes, restating that herd immunity was not the government's policy.
image copyright Getty Images The Telegraph website said the government had appeared to "U-turn on the idea".
The Express said herd immunity had been abandoned after "a huge backlash".
But despite repeated government denials, the BBC has learned that on 13 March, when Sir Patrick Vallance was outlining the government's approach to tackling the virus, herd immunity was being discussed at the heart of the health service.
"We want people to be infected with Covid-19," the notes say.
"The best way of managing it is herd immunity and protect the vulnerable."
Mr Enright was clear where the idea had come from, according to the notes.
"What it shows is that at the heart of the government's response there was no clear command-and-control structure as to how we were going to manage this outbreak.
"It's very important to get these facts on the record about herd immunity, because history is being rewritten at the moment and herd immunity is being written out of the history."
A government spokesperson said: "This is a new virus and an unprecedented global pandemic, and our strategy to protect, delay, contain, research and mitigate was clear from the outset.
It is categorically wrong to suggest herd immunity was the government's aim."
Suppression versus mitigation Some critics believe it is problematic if herd immunity was part of the government's thinking at the time.
Sir David King, former chief scientific adviser to the government between 2000 and 2007, has been a vocal critic of the UK government's efforts to fight coronavirus.
"I can only give you one rational explanation for this tragedy and that is that they had decided to go for herd immunity.
We did hear the phrase 'herd immunity', although the government subsequently somehow denied that they were doing that."
"We made the decisions at the time on the guidance of Sage [the government's scientific advisory group], including Prof Ferguson, that we thought were right for this country," he said.
The BBC has spent months speaking to more than a dozen scientists advising the government on its response to the outbreak to try to find out just how important the concept of herd immunity was to the scientific thinking that drove government strategy at the beginning of the outbreak.
Some of Sage's papers model different ways of responding to the outbreak.
"If a tsunami is coming we don't try to stop the tsunami, we just try to ensure that the minimum number of people are harmed by it."
"Herd immunity was on the table," says Prof Ian Hall, an epidemiologist, head of the University of Manchester modelling team, and a member SPI-M who has also attended multiple Sage meetings.
He described it "as a concept", a technical term typically used when discussing the spread of disease.
Dr Hall says SPI-M discussed a range of options to be able to prevent the NHS being overwhelmed and buy it time to prepare, while the population achieved "some sort of herd immunity".
Herd immunity can be achieved by an uncontrolled spread of infection which can happen quickly, but that would overwhelm the NHS.
Hall says this was never realistic because the government would always act to reduce the number of deaths.
But it can also be achieved by measures to mitigate the disease which look to protect lives, in the absence of any vaccine, and build up immunity over a long time.
Jeremy Hunt, chairman of the health and social care select committee, has criticised the scientific advice at the start of the pandemic, calling it "wrong".
"Ministers were given the choice of extreme lockdown or mitigated herd immunity," he recently told the Times newspaper.
He said that Sage did not model the adoption of a testing regime used in previous coronavirus outbreaks in East Asia.
image copyright Getty Images The need to "protect the vulnerable" had been mentioned repeatedly by the government and its advisers.
Graham Medley, chairman of SPI-M, gave an illustration of the challenges of delivering this when explaining herd immunity on BBC's Newsnight on 12 March.
He argued that theoretically - although impractically - one way to achieve it would be to move all vulnerable people to the north of Scotland, and the rest of the population to Kent.
That way "a nice big epidemic" in Kent would allow herd immunity and the re-mixing of the entire country again, he said.
"We can't do that, so what we're going to have to try and do, ideally, is manage this acquisition of herd immunity and minimise this exposure of people who are vulnerable."
Health Secretary Matt Hancock has on many occasions defended the government's handling of the outbreak in care homes, insisting that from the beginning it had tried to throw a "protective ring" around them.
Questions Four months on from the introduction of the lockdown, scientists remain unsure how long any immunity from coronavirus might last.
No-one knows when an effective vaccine will come.
But Dr Hall says the UK's response will ultimately end with herd immunity.
"Without a vaccine we will go on with transmissions at a relatively low level hopefully and with contact tracing and all the other interventions to mitigate the disease, we will eventually achieve herd immunity one way or another."

FOCUS AREAS CAREERS Programmes & Impact SUPPORTED COUNTRIES Gavi supported a total of 73 countries in 2018 FOR COUNTRIES OUR RESULTS Investing in Gavi GLOBAL VACCINE SUMMIT KEY AREAS #VaccinesWork FEATURED STORY COVAX explained 3 September 2020 News & Resources KEY PUBLICATION PROGRESS REPORT Search What is herd immunity?
The idea of herd immunity as the solution to the COVID-19 pandemic has triggered heated debate, but what is herd immunity and how does it work?
26 March 2020 What is herd immunity?
The idea of herd immunity as the solution to the COVID-19 pandemic has triggered heated debate, but what is herd immunity and how does it work?
26 March 2020 TOPICS: What is herd immunity?
Herd immunity is the indirect protection from a contagious infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection.
This means that even people who aren’t vaccinated, or in whom the vaccine doesn’t trigger immunity, are protected because people around them who are immune can act as buffers between them and an infected person.
Once herd immunity has been established for a while, and the ability of the disease to spread is hindered, the disease can eventually be eliminated.
This is how the world eradicated smallpox, for example.
What are the challenges in creating herd immunity?
The more infectious a disease, the greater the population immunity needed to ensure herd immunity.
For example, measles is highly contagious and one person with measles can infect up to 18 other people.
This means that around 95% of people need to be immune in order for the wider group to have herd immunity.
The new coronavirus has a lower infection rate than measles, with each infected person passing it on to two or three new people, on average.
This means that herd immunity should be achieved when around 60% of the population becomes immune to COVID-19.
However, natural herd immunity – achieved through infection rather than vaccination – can be challenging to induce through unchecked infection as there would be a very high rate of serious illness and death, with health systems overwhelmed well beyond their surge capacity, even in high-income countries.
This is why herd immunity is generally pursued through vaccination programmes.
Even when vaccines are available, it is not always possible to achieve herd immunity for very long.
Some viruses, such as seasonal flu, mutate frequently, evading the body’s immune response.
So immunity doesn’t always last forever, which is why the flu shot is necessary every single year.
Risks to herd immunity Mass vaccination has been highly successful in inducing herd immunity for many diseases, protecting those that are unable to build up immunity, such as people with immune deficiencies or whose immune systems are being suppressed for medical reasons.
When herd immunity is well established, however, some people choose to behave as ‘free riders’, essentially benefitting from everyone else getting vaccinated, while abstaining from vaccination either because they choose not to or are actively anti-vaccination.
When a population has too many of these free riders, the overall immunity level is compromised and herd immunity can be lost, putting everyone at risk.

From: Related terms: Download as PDF Set alert About this page D. Reid, D. Goldberg, in , 2012 Herd immunity Herd immunity is an important element in the balance between the host population and the micro-organism, and represents the degree to which the community is susceptible or not to an infectious disease as a result of members of the population having acquired active immunity from either previous infection or prophylactic immunization (see p. 731 ).
Herd immunity can be measured: 1 Indirectly from the age distribution and incidence pattern of the disease if it is clinically distinct and reasonably common.
This is an insensitive and inadequate method for infections that manifest subclinically.
2 Directly from assessments of immunity in defined population groups by antibody surveys (sero-epidemiology) or skin tests; these may show ‘immunity gaps’ and provide an early warning of susceptibility in the population.
Although it may be difficult to interpret the data in absolute terms of immunity and susceptibility, the observations can be standardized to reveal trends and differences between various defined population groups in place and time.
The decision whether to introduce herd immunity artificially by immunization against a particular disease will depend on several epidemiological principles.
• The disease must carry a substantial risk.
The effectiveness and safety of immunization programmes are monitored by observing the expected and actual effects of such programmes on disease transmission patterns in the community by appropriate epidemiological techniques.
URL: https://www.sciencedirect.com/science/article/pii/B9780702040894000822 Paolo Giorgi Rossi, Francesca Carozzi, in , 2019 Vaccination of boys Herd immunity is the main driver for the proposal of universal vaccination, that is, including boys and girls.
With growing evidence of the involvement of HPV in a relevant proportion of head and neck cancers, in particular oropharynx ( Plummer et al., 2016 ), it has become clear that the burden of vaccine-preventable disease in males is not negligible ( de Martel et al., 2017 ).
The vaccine has proven to be effective also on precancerous lesions of genital mucosae in males ( Palefsky et al., 2011 ).
Nevertheless, most models still predict that the largest benefit of vaccinating boys is the indirect effect on cervical cancer in women due to the reduction of circulating virus and to establishing of herd immunity faster ( Brisson et al., 2011 ).
The opportunity and cost effectiveness of vaccinating boys is still under debate, with the extreme heterogeneity of policies adopted in industrialized countries reflecting this uncertainty.
Given the very high incidence of HPV-related cancers in males having sex with males, there is consensus that vaccinating this group is opportune ( Markowitz et al., 2014 ; Kirby, 2015 ; Sauvageau and Dufour-Turbis, 2016 ), even though implementing effective strategies to target high-risk populations without indirectly fostering discrimination or stigmatization is challenging.
URL: https://www.sciencedirect.com/science/article/pii/B9780128012383651383 Catherine J. Luke, ... Kanta Subbarao, in , 2013 Herd immunity and indirect protection from LAIV Herd immunity is defined as the proportion of persons with immunity in a given population, 180 and the indirect protection afforded by this immunity to the unimmunized segment of the population is defined as the herd effect .
Herd immunity has been demonstrated for infectious diseases of viral and bacterial etiology, and it is widely accepted that this phenomenon occurs with influenza.
190 Excess mortality rates in Japan increased with discontinuation of the vaccination program for schoolchildren.
From a practical standpoint, LAIV could be an extremely effective method to achieve herd immunity if high vaccination rates with an efficacious vaccine are achieved in schoolchildren and influenza transmission to other segments of the community is interrupted.
Large numbers of children could be vaccinated in a short period of time, and intranasal administration is preferred over injection of inactivated vaccine.
The data from these studies support the widespread vaccination of schoolchildren as a means of reducing morbidity and mortality in other high-risk members of communities.
URL: https://www.sciencedirect.com/science/article/pii/B9781455700905000276 In , 2012 Summary • Herd immunity forms the theoretical basis for mass vaccination programs.
• In the twentieth century, mass vaccination programs were highly successful in eradicating childhood diseases such as diphtheria, pertussis, and tetanus.
• Viral antigens often change as a consequence of antigenic drift, antigenic shift, or genetic reassortment.
URL: https://www.sciencedirect.com/science/article/pii/B9780323069472100252 JOHN P. FOX, LILA R. ELVEBACK, in , 1975 In 1971, we discussed herd immunity and its relevance to immunization practices ( 1 ), using applications of the Reed-Frost epidemic model ( 2 ), and of a stochastic simulation model for a community of families ( 3 ) to illustrate the basic concepts.
This presentation draws heavily on our previous discussion * but also will consider how these concepts of herd immunity relate to some important current immunization problems.
The case was in a 3-child family and a 5-child play group and did not attend nursery school although his 2 siblings were among the 40 susceptibles who did attend.
URL: https://www.sciencedirect.com/science/article/pii/B9780125220507500204 Paul E.M. Fine, ... W. John Edmunds, in , 2018 Case Reproduction Numbers We can approach this herd immunity concept from an alternative, and equally informative, perspective.
If an infection is to persist, each infected individual must, on average, transmit the agent to at least one other individual.
5] R n = R 0 × S By this expression, if the proportion susceptible ( S ) were equal to the reciprocal of the basic reproduction number of the infection (1 / R 0 ), the average number of transmissions per case ( R n ) should be 1, and thus incidence should remain constant over time.
77.5B illustrates this, and it once again leads us directly to the herd immunity threshold ( H ).
Because the proportion immune is just the complement of the proportion susceptible ( H = 1 − S ), we have [Eq.
77.6 shows the relationship graphically, which shows the implications for persistence or decline of an infection depending on its basic reproduction number and the proportion of immune persons in the population.
1,13,16 URL: https://www.sciencedirect.com/science/article/pii/B9780323357616000778 Emmanuel Vidor, Stanley A. Plotkin, in , 2013 Herd immunity The best evidence for a herd immunity effect of IPV is the experience in the United States where IPV was introduced into routine use in 1955 and was replaced by OPV in 1962.
A sharp drop in the numbers of cases of paralytic and nonparalytic polio was evident during the years 1955 to 1962 ( Figure 27-5 ).
214 More specific regional data were published that suggested a greater than expected reduction in polio cases.
215 The second example of herd immunity comes from the Netherlands where vaccination is refused by a religious community that is well dispersed throughout the country, although IPV is routinely administered to the rest of the population.
Two outbreaks of polio have occurred in this religious group, one caused by type 1 virus in 1978 (110 cases) and the second by type 3 virus from 1992 to 1993 (71 cases).
Proof of recent type 3 infection was found in 59.5% of the unvaccinated children and in 22.2% of the vaccinated children.
The evidence for herd immunity comes from countries where oral-to-oral transmission was probably the dominant mode of interhuman poliovirus transmission.
It is less clear if IPV is able to induce herd immunity in countries where the fecal-to-oral route is thought to be the primary role in transmission.
URL: https://www.sciencedirect.com/science/article/pii/B9781455700905000343 RICHARD C. ROSATTE, ... DAVID H. JOHNSTON, in , 2007 10.2 Bait density Control ultimately depends on establishing herd immunity through animals taking baits and sero-converting.
Hence, bait density must correlate with animal density in some positive fashion ( Rosatte and Lawson, 2001 ).
(unpublished); f Matouch and Vitasek (2005) ; g Bigler and Lein (2001) ; h Nohrenberg, USDA(unpublished).
URL: https://www.sciencedirect.com/science/article/pii/B9780123693662500208 David S. Stephens, Michael A. Apicella, in , 2015 Herd Immunity and Introduction Strategies Protection against the bacterial meningitis pathogens through herd immunity is a remarkable, powerful, and unanticipated effect of bacterial polysaccharide-protein conjugate vaccines.
35 Herd immunity can account for approximately one half of their effectiveness at preventing disease and has significantly enhanced their cost-effectiveness.
It is an important strategy for vaccine introduction, implementation, and evaluation.
As noted, in 1999 to 2000 the meningococcal serogroup C conjugate vaccines were introduced in the United Kingdom as a broad catch-up campaign for those younger than 19 years of age, reduced nasopharyngeal carriage of serogroup C in adolescents more than 75%, and created herd immunity that has persisted for more than a decade.
413,417 The explanation for this remarkable herd immunity effect is the low R 0 (basic reproduction number, or the average number of secondary infectious cases that are produced by a single index case in completely susceptible population), estimated at 1.3, for meningococcal disease providing herd immunity with 17% to 26% vaccine coverage of the population.
35 ,434 In contrast, measles, mumps, pertussis, polio, and rubella have an R 0 greater than 5 and require much higher thresholds (i.e., >80% for herd immunity).
427 The immunologic basis of mucosal (herd) immunity with conjugate vaccines remains unclear.
Generation of capsule-specific mucosal immunoglobulins, transudation of high-avidity serum IgG to mucosal surfaces, and Th17-induced immunity via macrophage clearance have been proposed.
35 Cost-effectiveness, measured as a quality-adjusted life-year (QALY) score, is increasingly becoming an important consideration of vaccine recommendations in public health.

Experts speak out CORONAVIRUS is still dominating the conversation - restricting where people can go, who they can see and what they can do.
As the world sits on the edge of their seat waiting for a vaccine, would herd immunity ever work?
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However, could there have been a better way?
Could herd immunity have worked more effectively?
In March, there was talk of allowing the virus to "pass through the entire population so that we acquire herd immunity".
READ MORE: Coronavirus: Would herd immunity work?
(Image: Getty) However, this approach was quickly dismissed, with a statement put out on March 15 by Health Secretary Matt Hancock.
"We have a plan, based on the expertise of world-leading scientists.
Herd immunity is not a part of it.
"That is a scientific concept, not a goal or a strategy.
"Our strategy is to protect the most vulnerable and protect the NHS through contain, delay, research and mitigate."
DON'T MISS... [SHOCK] [REVEAL] [INSIGHT] Related articles Academics from the London School of hygiene and Tropical Medicine noted a "common implication" of herd immunity.
They identified herd immunity implies "the risk of infection among susceptible individuals in a population is reduced by the presence and proximity of immune individuals".
The Vaccine Knowledge Project at Oxford University explained herd immunity "only works" if the majority of the population has been vaccinated against the disease.
In addition, herd immunity "does not protect against all vaccine-preventable diseases".
COVID-19 has resulted in buisness closures (Image: Getty) READ MORE Professor Mark Woolhouse, of infectious disease epidemiology at the University of Edinburgh, told the Independent that the concept of herd immunity is "the basis of all vaccination programmes".
This points towards the idea that herd immunity can only be achieved after a safe and effective vaccine has been rolled out.
Yet, this isn't the case according to Professor Woolhouse, who stated herd immunity can arise naturally.
He explained: "If you’ve been exposed to any infection, enough people have already been exposed to it, have developed antibodies and they’re immune to it."
Related articles Herd immunity could be effective after vaccinations (Image: Getty) Why was this idea taken off the table so quickly when the first wave of coronavirus came round?
Tonia Thomas, Vaccine Knowledge project manager, said enabling the population to catch the virus could lead to long-term complications in people.
Moreover, research is still discovering how long COVID-19 antibodies remain in a person's system, which would be required for immunity.
In addition, so many people would have fell ill, and the NHS was already struggling, so a lot more deaths would have been likely.

Its lead authors, the Times said, include Jay Bhattacharya, MD, an economist and medical professor at Stanford University, the academic home of Scott Atlas, MD, President Trump’s science adviser.
Atlas has also publicly supported herd immunity.
View this post on Instagram Signing!
Let’s do this and restore life back to normal using #Focusedprotection leading to #Herdimmunity.
#Gbdeclaration A post shared by Great Barrington Declaration (@gbdeclaration) on Oct 10, 2020 at 2:42am PDT The declaration’s signatories include Sunetra Gupta, PhD, and Gabriela Gomes, PhD, two scientists who say herd immunity can be achieved when 10% to 20% of a population has been infected with the virus.
“Current lockdown policies are producing devastating effects on short and long-term public health,” the declaration states.
“The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up to the virus through natural infection, while better protecting those who are at highest risk.” Within hours of the White House call supporting the Barrington declaration, public health experts condemned the Trump administration’s embrace of the declaration and its approach.
“It’s a ghastly way” to combat the virus, said William Schaffner, MD, professor of infectious diseases at Vanderbilt University School of Medicine.
It also coincides with new projections that don’t support Trump’s pledge to have a COVID-19 ready by Nov. 3.
The concept of herd immunity comes from livestock farming and refers to the point at which a disease stops spreading because nearly everyone has gotten it, thereby providing immunity.
In June, researchers from the University of Nottingham and University of Stockholm that herd immunity might be achieved when 43% of a population becomes immune to the coronavirus.
“High-risk individuals live, work, and come into contact with low-risk individuals in the same communities, in the same households,” he noted.
“How can these two groups actually be physically separated, as would seem to be necessary under the focused protection plan?” In addition, it remains unclear whether infection with COVID-19 confers immunity from reinfection.
There are several case “We can expect that more and more reinfections will occur over time as natural immunity wanes,” he said.
“You may never be able to reach that magic 'herd immunity' threshold at all if people can be re-infected.” For these reasons, he endorses most public health specialists’ views -- including those of many of Trump’s own coronavirus task force -- that the best way to combat and control coronavirus is through COVID-19 testing, contact tracing, isolation and quarantine, mask use, and social-distancing measures that reduce crowding.
“There are many examples of countries that have done just that, and have reaped economic and social benefits from that approach,” he said.
More Scientists Weigh In Michaud and Schaffner’s sentiments were echoed by the authors of a letter published in medical journal late yesterday.
The group of 80 researchers and epidemiologists warned that a “herd immunity” approach is “a dangerous fallacy unsupported by the scientific evidence.” They state: “It is critical to act decisively and urgently.
Effective measures that suppress and control transmission need to be implemented widely, and they must be supported by financial and social programs that encourage community responses and address the inequities that have been amplified by the .” Proud to be a signatory of the .
This statement, out now in , is the scientific consensus on the COVID-19 pandemic directly refutes the Great Barrington Declaration proposal of "focused protection" as a route to herd immunity.
— Dr. Angela Rasmussen (@angie_rasmussen) Some public restrictions will be needed in the short term, they said, to lower the spread of the virus and correct problems in pandemic response systems.
It preys on a frustrated populace.
Instead of selling false hope that will predictably backfire, we must focus on how to manage this pandemic in a safe, responsible, and equitable way.” “The idea that herd immunity will happen at 10 or 20 percent is just nonsense,” said Christopher J.L.
Murray, MD, DPhil, director of the University of Washington’s , which produced the epidemic model frequently cited during White House news briefings as the epidemic hit hard in the spring.
WebMD Health News Reviewed by Sources William Schaffner, MD, Vanderbilt University.
The Lancet: "Herd immunity approaches to COVID-19 control are a ‘dangerous fallacy’, say authors of open letter."
The New York Times: " White House embraces a declaration from scientists that opposes lockdowns and relies on ‘herd immunity.’" Joshua Michaud, PhD, associate director, Global Health Policy, Kaiser Family Foundation.
The White House: “Background Press Call on the Trump Administration's Strategy to Safely Reopen America.
Will add press release transcript to documents.” Science : "A mathematical model reveals the influence of population heterogeneity on herd immunity to SARS-CoV-2."
Medicalxpress.com: “Herd immunity threshold could be lower according to new study.” Big Cities Health Coalition: “17 Public Health Organizations Condemn Herd Immunity Scheme for Controlling Spread of SARS-Cov-2.” Christopher J.L.