CD8A and susceptibility to pneumonia measurement: In particular, according to Du’s findings, CD3+CD8+ T cells ≤ 75 cells/μL, associated to age ≥ 65 years, pre-existing concurrent cardiovascular or cerebrovascular disorders, and cardiac troponin I ≥ 0.05 ng/mL, were significantly associated with increased risk of death in patients with pneumonia caused by SARS-CoV-2 [46].