CCL20 and infection: Consistent with previous report (27), we also observed overexpression of cytokines and chemokines (CC)-related genes in the severe COVID-19 patients during their early stage of infection, including pro-inflammatory cytokines or chemokines such as IL1A, IL1B, IL10, TNF, CCL20, CCL3, CCL4, CXCL1, CXCL2, CXCL3, and CXCL8 (Figure 5C).