IGHA1 and COVID-19: Here we characterized serum RBD-specific antibody classes and subclasses, including IgG1, IgG2, IgG3, IgG4, IgM, IgA, IgA1 and IgA2, in a longitudinal cohort of SARS-CoV-2 naïve and COVID-19 recovered individuals who received the mRNA-1273 vaccine.