CD79A and COVID-19: The purpose of the current study was to investigate the immunogenicity of booster vaccination induced by an initial monovalent mRNA vaccine followed by additional monovalent or bivalent boosters against COVID-19 by examining the induced anti-SARS-CoV-2 IgG and IgA antibodies; and to examine the effectiveness of repeated booster vaccination in reducing the risk of severe disease and/or death from disease.