Several studies about COVID-19 vaccines have shown that PLWH with CD4+ T cell counts ≤500 cells/μL (21), ≤350 cells/μL (22), and especially those with <200 cells/μL, exhibit lower severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG and neutralizing antibody (NAbs) titers and seropositivity rates relative to PLWH with higher CD4+ T cell counts after COVID-19 vaccination. This evidence concerns the gene CD4 and COVID-19.