CD8A and COVID-19: COVID-19 and IPF lungs shared key features: the depletion of alveolar macrophages and AT2 cells, increased monocyte-derived macrophages (Mo-Macs) and CD8+ T cells, and upregulation of fibrosis- and inflammation-related genes (e.g., SPP1, S100A8/A9, and COL1A1/3).