The term ‘group immunity’ has been invoked time and again by the media and in almost every vaccination discussion. Opponents argue that group immunity “does not work” and, above all, wants to respond to feelings of guilt. Do people who are not vaccinated endanger others?
Group immunity also referred to as “herd immunity”, is described as nonsense on various forums and websites. Other websites, such as the World Health Organization’s, state that vaccination protects not only yourself but other vulnerable children and adults as well. To create clarity, some knowledge about vaccination is necessary.
Vaccines and Herd Immunity
You get a vaccine primarily to protect yourself. If a lot of people are vaccinated, the effect of group immunity can occur, as a result of which the pathogen can no longer spread among the vaccinated population and so can no longer reach the unvaccinated people. Non-vaccinated persons have therefore protected thanks to those around them who have been vaccinated.
Related: If you are in Canada and you want to sponsor siblings to Canada, you ought to know that Canada has strict rules in immigration and this includes quarantine and vaccination for health and security purposes. So if your siblings have not gone through required major vaccinations, you might as well reconsider or have them complete their vaccinations before travel.
The minimum vaccination coverage to be achieved for this depends on the type of pathogen and the effectiveness of the vaccine. For example, for measles, 95% of the population must be vaccinated or immune. By “immune” is meant that you, for example, experienced the disease as a child. Since measles is highly contagious and each new case can infect an average of 18 other people, this disease requires vaccination of 95% of the population so that the virus has no chance of spreading and infecting the remaining 5%.Unlike other drugs, vaccines are administered not only to protect the individual but also to protect the community. This is called group protection or herd protection, a concept from veterinary medicine: when enough people are vaccinated or immune to a certain disease, the relevant germ has no chance to spread. In fact, all vaccinated and immune people together form a “buffer” against the spread of the germ (virus or bacteria) within the group.
There are still preconditions for the principle of group protection to work: it only applies to germs that are passed on from person to person, and the still susceptible people must be spread over the general population. As soon as unvaccinated persons form a closed community, group protection no longer works for them.
The remaining 5% may include people who should not be vaccinated for a variety of reasons, such as disease of their immune system or cancer treatment. In addition, vaccines do not provide 100% protection, and people who are ultimately not protected after vaccination must also be able to count on protection in society. For example, they can be protected indirectly, through group protection. Any reduction in such group protection would endanger these people and society, as current measles epidemics in Europe show.
A sufficiently high vaccination coverage ensures group protection, which is a kind of buffer against the spread of vaccinable infections in society. For measles, a vaccination rate of 95% must be achieved to stop the spread among the population. In this way, people who are not allowed to be vaccinated, for example, for medical reasons, can also be indirectly protected.