CD8A and COVID-19: This phenomenon was observed in alveolar macrophages (0.25%/0.28% positive in mild/severe COVID-19 patients), SPP1+ macrophages (0.23%/0.23%), M1-like macrophages (2.60%/0.43%), CD8+/NK cells (7.75%/4.18%), proliferating T cells (2.00%/3.60%), plasma cells (cells not detected/0.74%), neutrophils (0%/0.05%), and epithelial cells (0.29%/0.18%).