CD79A and infection: In contrast, breakthrough infection donors mounted significantly higher magnitude IgA responses to the RBD, with WT and BA.1 RBD-specific IgA+ B cells accounting for a median of 0.13% (ranging 0.05 to 0.7%) and 0.069% (ranging 0.025 to 0.4%), respectively, of the total IgA+ B cell population (Fig. 2B).