CD79A and infection: Natural infection induces and boosts IgA and IgG in oral fluid and serum; vaccination does not induce or boost specific saliva IgA; IgG can be found in saliva after vaccination, but only when serum IgG concentrations are high; IgA is important for SARS-CoV-2 neutralisation activity by oral fluid, but there can also be contributions from serum IgG and other factors.