At variance with the IgG response, IgA avidity was not significantly different between T1 and T2 [AIT1 = 3.54 (2.77–4.73); AIT2 = 4.05 (2.97–5.42)] and between vaccinated subjects and COVID-19 patients [AI = 3.51 (3.04–5.09)] (Figure 3C,D). This evidence concerns the gene CD79A and COVID-19.