As new COVID variants emerge, is herd immunity impossible?

The significantly more transmissible Delta variant means even higher numbers will have to be fully vaccinated to achieve any sort of herd immunity.

Herd immunity is a term that has been bandied around since the beginning of the coronavirus pandemic. It occurs when a large proportion of a population becomes protected against or immune to infection, significantly reducing the spread of that infection even in the unprotected group. It can be achieved through the following: