Community (herd) immunity
If enough people in a community are immunised against an infectious disease, there is less of the disease in the community, which makes it harder for the disease to spread.
Immunisation protects both people who are vaccinated and also helps the entire community. It helps protect those who are too young to be vaccinated and those who can’t be vaccinated for medical reasons. This is known as community (herd) immunity.
Page last updated: 04 Aug 2017