Indeed, previous reports demonstrated that mainly CD4+ T cells elicit robust cytokine responses against S-protein peptide pool after rechallenge in convalescent individuals with COVID-19, suggesting that cytokine profiles against S-protein in both convalescent individuals with COVID-19 and vaccinated donors overlap (11) and S-protein may favor the generation of SARS-CoV-2–specific CD4+ T cells. This evidence concerns the gene CD4 and COVID-19.