CD8A and COVID-19: However, there were age-dependent decreases in CD8+ T cell count in both male (young cohort 332 cells/μL [IQR 239–502] vs. old cohort 216 cell/μL [IQR 133–321], p < 0.001) and female (young cohort 374 cells/μL [IQR 285–493] vs. old cohort 226 cell/μL [IQR 143–392], p < 0.01) COVID-19 patients.