CD79A and infection: Following three vaccinations, the group who remained uninfected (n = 49) had stronger vaccine-induced plasma IgA responses against FLS (median OD ± IQR 0.50, 0.31–0.76 vs. 0.28, 0.17–0.61, p = 0.0471) and RBD (0.24, 0.13–0.46 vs. 0.13, 0.05–0.46, p = 0.0266) compared to subjects (n = 47) who later experienced breakthrough infections (Figure 2a,b).