The difference in IFN-γ levels between clinical groups (PID, SID and HC) remained statistically significant after adjusting for age, sex, time since last exposure to SARS-CoV-2 antigens (vaccination or natural infection) and past history of natural SARS-CoV-2 infection with logistic regression (LR test, p = 0.016). The gene discussed is IFNG; the disease is infection.