However, we observed that IFN-γ, TNF-α, and IL-2 production by vaccine-induced SARS-CoV-2–specific CD4+ and CD8+ T cells was variable across the 21 vaccinated individuals (Figure 2B), suggesting that vaccination may provide a differential level of protection against COVID-19 due to varied magnitude of vaccine-induced SARS-CoV-2–specific T cell response. This evidence concerns the gene CD4 and COVID-19.