A large number of studies have shown that SARS-CoV-2 infection can cause a more pronounced lymphocytopenia in patients with moderate and severe COVID-19, as reflected by the decreased level of T cells, including Th1, Treg, and CD8+ T cells.1,39,40 In addition, neutrophils increased and monocytes decreased in COVID-19 patients.39,41 These abnormalities may be reversed in some immune cells after recovery. This evidence concerns the gene CD8A and COVID-19.