Experts do not know what percentage of people would need to get vaccinated to achieve herd immunity to COVID-19. Herd immunity (community immunity) is a term used to describe when enough people have protection—either from previous infection or vaccination—that it is unlikely a virus or bacteria can spread and cause disease. As a result, everyone within the community is protected even if some people don’t have any protection themselves. The percentage of people who need to have protection in order to achieve community immunity varies by disease.