CD79A and infection: In individuals without prior SARS-CoV-2 infection, mucosal IgA responses after intramuscular (IM) SARS-CoV-2 vaccination appear relatively weak and short-lived.22, 23, 24 Intranasal (IN) SARS-CoV-2 vaccination is thus immunologically attractive, and potentially complementary to the effectiveness of intramuscular SARS-CoV-2 vaccination against severe systemic consequences of infection.25