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.