CD79A and COVID-19: Since the reports available so far on the mucosal IgA response following booster vaccination refer almost exclusively to the BNT162b2 (Pfizer-BioNTech) vaccine, in this study, we wanted to characterize the development of oral IgA mucosal immunity in response to the different combinations of COVID-19 vaccine formulations used for the vaccination campaign in Italy, including the A (Astra-Zeneca), M (Moderna), and P (Pfizer-BioNTech) vaccines.