PDCD1 and COVID-19: The CD4 subset including Th EMRA-Tim-3+ (Median 6.2; Q1-Q3 -3.7-18.6 vs. Median 2.35; Q1-Q3 0.65-6.15; p=0.004), Th Naive-PD1+ (Median 5.45; Q1-Q3 -1.9-152 vs Median 4.4; Q1-Q3 2.4-7.2; p<0.0001), Th-EM (effector memory)-PD1+ (Median 67.45; Q1-Q3 -59.2-79.6 vs. Median 59.15; Q1-Q3 45.1-64.8; p<0.0001), Th EM-Tim 3+ (Median 5.65; Q1-Q3 -4.0-11.3 vs. Median 0.5; Q1-Q3 0.3-0.85; p=0.009), and Th CM (central memory)-Tim-3+ (Median 2.4; Q1-Q3 -1.3-4.5 vs. Median 0.5; Q1-Q3 -0.3-0.85; p<0.0001) showed a significantly higher in severe COVID-19 patients as compared to control.