CD79A and infection: Both SARS-CoV-2 vaccination and infection generate IgA responses against S, RBD, and N (25, 26); however, the serum IgA dynamics over time following infection of previously vaccinated individuals is still unclear, and the cross-reactivity with HCoV at the IgA level, as well as serum IgA’s potential utility as a marker of recent infection, remains poorly understood.