CD8A and COVID-19: In both cohorts, KLRG1 was highly expressed among CD8+ T cells (71.2% ± 2.7 in COVID-19+ versus 67.5% ± 19.8 in control group, p = ns) followed by CD57 (40.2% ± 1.6% versus 32.5% ± 20.2, p = ns), whereas CD56 and NKG2A were weakly if not expressed (14.5% ± 2.1 versus 9.3% ± 7.6 and 4.1%, SD: 1.1% versus 2% ± 0.9 respectively, p = ns).