CD8A and COVID-19: Actually, studies on adaptive immune responses to SARS-CoV-2 demonstrated that CD4+ T cells had a strong response to Spike protein and were correlated with the titers of the anti-SARS-CoV-2 antibody, and it is reported that the SARS-CoV-2-specific CD4+ T cells are detectable in 100% of recovered COVID-19 patients, while the detection rate of CD8+ T cells is only about 70% (46).