How do you calculate herd immunity?

Rachel Thomas

Rachel Thomas

Herd immunity happens when so many people in a population are immune to a disease that the epidemic is forced into decline, even though there are still people around who can catch and spread the disease. Early on in the coronavirus pandemic, researchers estimated the herd immunity threshold for Covid-19 to be 60%, but where does this number come from?

Find out with Plus editor Rachel Thomas, who talked about the herd immunity calculation on the Guardian Science Weekly podcast in May 2020.

Listen to the Guardian's Science Weekly podcast (external link).