Figure 2. Blood lymphocyte and subset count, plasma C-reactive protein (CRP) and interleukin 6 (IL-6) levels in COVID-19 patients with different age categories. (A) Lymphocyte counts linearly decreased in the five age groups. (B) B cells did not significantly differ among the five age groups. (C) Natural killer (NK) cells did not differ among the five age groups. (D) Changes in T cell counts in the five age groups. (E) CD4+ T cells did not significantly differ among the five age groups. (F) CD8+ T cell counts linearly decreased in the five age groups. (G) Correlation between age and CD8+ T cell counts. (H) CRP levels linearly increased in the five age groups. (I) Changes in IL-6 levels in the five age groups. *p<0.05, **p<0.01, and ***p<0.001 vs. age group 2–25y; †p<0.05, ††p<0.01, and †††p<0.001 vs. age group 26–38y; and ǂ p<0.05 vs. age group 39–57y.