Using correlates to accelerate vaccinology
There have been many reports of large-scale vaccine studies showing that various severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines give almost complete protection against severe COVID-19 and incomplete but dwindling protection against infection of the nose and lungs. Given the costs and difficulty of field studies involving thousands of people, which are necessary to show vaccine efficacy, the hunt for immune correlates of protection (COPs; laboratory measurements that predict the outcomes of large-scale studies) has become intense. On pa ge 43 of this issue, Gilbert et al. (1) report the use of a technique called mediation analysis to examine data from a trial of the mRNA-1273 vaccine from Moderna to infer that virus neutralizing antibody (VN-Ab) accounts for ∼60% of protection. They propose that VN-Abs might provide a reliable COP, which could be used to support the approval of future COVID-19 vaccines, bypassing the need for large trials.