Furthermore, a clearly diminished CD154+ CD4+ (0.1 ± 0.17 vs. 0.55 ± 0.83; p = 0.15), IFN-γ+ CD4+ (0.37 ± 0.4 vs. 0.73 ± 1.64; p = 0.83), and CD154+ IFN-γ+ CD4+ (0.08 ± 0.07 vs. 0.19 ± 0.38; p = 0.56) T-cell response was observed after the second BTN162b2 dose in the patients with previous SARS-CoV-2 infection compared to the non-previous infection group. This evidence concerns the gene CD4 and infection.