1. 2. News and Media 3. Herd Immunity: How does it work? -- Herd Immunity: How does it work? Share Share -- -- 26 April 2016 Dr Manish Sadarangani explains how herd immunity works and why vaccinating children is important. -- -- vaccinating children is important. Q: What is herd immunity? -- 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. In this -- -- 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. -- -- need to be vaccinated. Herd immunity People are shown as circles. Infectious agents (germs) spread between the people in orange, although they do not get severe disease. When the infection reaches people who are highly susceptible -- -- 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 -- -- 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 -- -- 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. -- -- 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 -- -- 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, measles 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 -- -- 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 polio is less contagious, and -- need to be vaccinated. A disease like polio 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? -- MS: No. Herd immunity only works for diseases that are spread directly between people (i.e. are ‘contagious’), like measles. One example where it would not work is tetanus. The bacteria which cause tetanus lives in -- -- + Cookies * News and Media + Herd Immunity: How does it work? + It’s World Immunisation Week! + Partnership announces publication of positive phase 1 data for -- -- recruitment + Funding for new COVID-19 studies awarded to OVG's project on infectious disease immunity in children + Paediatrics project receives funding to assess novel coronavirus infection rates in children and teenagers across -- -- + Trial of Oxford COVID-19 vaccine in South Africa begins + Ebola vaccine approved for use by the European Commission + OVG study sheds light on coronavirus immunity in children + New study reveals Oxford coronavirus vaccine produces strong immune response -- -- + Competently maximize high-quality processes before value-added users. + Hot Topics In Infection And Immunity In Children 2016 + Hot Topics In Infection And Immunity In Children 2017 + Oxford Vaccine Group Immunisation Seminar -- + Oxford Vaccine Group Immunisation Seminar + Hot Topics In Infection And Immunity In Children 2018 - The ESPID-Oxford Course + Immunisation Seminar