CCL4 and COVID-19: Among the cytokines over-expressed in COVID-19 are those generally linked to innate immunity, including pro-inflammatory cytokines (e.g. IL-6, TNF-α, IL-1β), chemokines (e.g. CXCL10/IP-10, CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, and IL-8), immunoregulatory cytokines (e.g. IL-10, TGF-β), and growth factors (G-CSF) (5–11).