Quixplained: What is herd immunity, how it works

How herd immunity works?

Herd immunity is a stage of an epidemic in which some members of a population group remain protected from infection because a majority of those around them have already developed immunity, either through vaccination or because they have been infected earlier.

So, everyone in the population group does not need to get infected before the epidemic is over.

Once a certain proportion of population gets infected, and thus builds immunity against the disease, the epidemic begins to slow down and eventually stop.

It is extremely difficult to determine the level of disease spread necessary for herd immunity when the epidemic is still raging.

Text: Amitabh Sinha; Illustration: Mithun Chakraborty