CD4 and COVID-19: Compared with the hub targets of single disease (COVID-19), it is found that TNF, IL-6, IL-1β, CD4 and Albumin (ALB) are common (Figure 2B), indicating that these five targets not only play an important role in the common pathogenesis of COVID-19, RA, AS and GA, but also play a core role in the pathogenesis of single disease (COVID-19) and are potential targets for the treatment of COVID-19.