SARS2 and infection: Given that nonstructural proteins are expressed earlier in infection and are better conserved across human coronaviruses, it is possible that the inclusion of nonstructural protein epitopes in our peptide megapools allows for earlier and more comprehensive detection of both cross-reactive and SARS2-specific circulating T cell responses than peptide pools containing only SARS2 structural protein epitopes (38, 52, 53).