“Herd 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.
Initial estimates from the World Health Organization indicated that at least 70% of a given population would have to be vaccinated in order to achieve “herd immunity”. However, many scientists, including Dr. Anthony Fauci, have revised the initial estimate upward to the 70 to 90% range. The bottom line is that the more people who get vaccinated in a community, the greater the chances are of diminishing the spread of the disease to the point where it can be managed and no longer presents a public health crisis.