While many studies have documented that CD4 and CD8 T cells elicited by mRNA vaccines strongly correlated with more positive outcomes following infection with SARS-CoV-2, and that these T cell responses are long lived (6–13), incisive studies to determine the protective mechanisms, tissue distribution of memory T cells, or the kinetics of the T cell response at an organ-by-organ level are not possible in humans. The gene discussed is CD8A; the disease is infection.