CD79A and infection: Other studies also have pointed out the additional value of IgA-Ptx measurements in serodiagnostics [28, 31, 38, 39]; the notion being that exposure to B. pertussis antigens through infection will lead to both IgA-and IgG-Ptx production [30] while exposure by (aP) vaccination alone will generate IgG but less IgA to Ptx [40].