CD4 and COVID-19: In patients with severe COVID‐19, lymphopenia resulted from drastically reduced numbers of NK, CD8+ T, CD4+ T and B cells, but not in patients with mild or moderate disease2, 6, 7, 8; these studies mainly focused on the correlation between lymphocyte count and COVID‐19 severity, as no results on the change in the number of NK cells and lymphocyte subsets in patients with moderate COVID‐19 were reported.