Our new paper was just published as a direct submission in PNAS and covered in this press release. Here we introduce the concept of “transient collective immunity” and argue that it described COVID-19 epidemics better than a more familiar concept of “herd immunity”. The main difference between these two concepts is that transient collective immunity is not expected to last forever. This is similar to the transient nature of biological immunity caused by decreasing antibody counts and the emergence of new variants. However, in our case, this “expiration date” is caused entirely by changes in levels of individual social activity.
