CD8A and COVID-19: Lymphocytopenia is a common feature in patients with severe COVID-19, with a dramatic decrease in the number of CD4+ and CD8+ T cells, B cells, and natural killer (NK) cells (5, 17–19) and lower proportions of monocytes, eosinophils, and basophils among leukocytes (18, 20); in particular, patients with higher N/LRs have poorer outcomes (20).