CD4 and COVID-19: Lower CD4+ T cell counts (P=0.0121), higher CD8+ T cell counts (P=0.0533), and an abnormal CD4+/CD8+ ratio (P=0.0131) were observed in men of the moderate COVID-19 group, and severe symptoms were associated with lower CD4+ and CD8+ T cell proportions in all patients, with much lower proportions in severe males (Figure 4B,C and Supplementary Tables S4 and S5).