CD79A and COVID-19: IgA-S1 in nasal secretions showed higher median IgA values in vaccinated and COVID-19 subjects (7.56 and 6.44 COI, respectively) compared to the healthy controls (0.86 COI) (Table 4 and Figure 3a) (p-value = 0.001 between COVID-19 subjects vs. healthy controls and p < 0.0001 between vaccinated subjects vs. healthy controls), considering 0.86 COI as the cut-off value.