IFN-γ levels significantly declined in the controls (P < 0.0001), XLA (P = 0.047), CVID (P < 0.0001) and IgG/SPAD (P < 0.0001) cohorts 6 months after the second vaccination compared to 28 days after vaccination (Fig. 4A), but not in the CID (P = 0.19), phagocyte defects (P = 0.25) and undefined antibody deficiency cohorts (P = 0.23). This evidence concerns the gene IFNG and agammaglobulinemia.