CD8A and COVID-19: Figure 4A shows the distribution of 28 immune cells in the two groups of samples, and the results show that central memory CD8 T cells, T follicular helper (Tfh) cells, regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), plasmacytoid dendritic cells (pDCs), macrophages, eosinophils, and neutrophils infiltrated significantly more the tissues of patients with COVID-19 than normal tissues (p<0.05), suggesting that these immune cells are essential for the development of COVID-19.