Tracking immune correlates of protection for emerging SARS-CoV-2 variants.

Reliable SARS-CoV-2 correlates of protection (COP) are crucial for predicting individual-level risk of infection, estimating population susceptibility, and assessing future epidemic risks.1 However, COP studies are challenging given that blood samples ideally need to be collected close to the time of exposure, which is hard to predict. Thus, most existing SARS-CoV-2 COP estimates are based on vaccine efficacy trial data,2,3 which include frequent blood sampling and strict infection monitoring and are therefore well suited for this purpose.