A total of 4 out of these 10 PID patients (40%) who had COVID-19 prior to vaccination (1 patient with bilateral pneumonia and the rest with mild symptoms) showed higher specific anti-SARS-CoV-2 IFN-γ production than those without previous disease, as expected, 270 (68.7–1375) mUI/mL vs. 1.1 (0–17) mUI/mL. This evidence concerns the gene IFNG and COVID-19.