TLR4 and COVID-19: Based on the Degree, MCC, Closeness, Betweenness, and MNC algorithms of the CytoHubba plug-in, six genes (FPR1, FCGR2A, TLR4, S100A12, CXCL1, and LTF) were confirmed as hub genes related to COVID-19 severe (Figure 4B, Table S5).