Figure 5B illustrates the distribution of 22 immune cells in COVID-19, and the infiltration of plasma cells, memory resting CD4 T cells, monocytes, M0 macrophages, resting mast cells and neutrophils in tissues from patients with COVID-19 is considerably higher than that in normal tissue (p < 0.05). Compared to the normal group, the proportion of activated CD8 T cells and natural killer (NK) cells in patients with COVID-19 is lower. Moreover, Figure 6 depicts the relationships between the 22 immune cells. The gene discussed is CD8A; the disease is COVID-19.