CCL4 and COVID-19: In COVID-19 patients, there were too much of certain proteins called cytokines, including IL-1β, IL-1RA, IL-7, IL-8, IL-9, IL-10, basic FGF, G-CSF, GM-CSF, IFN-γ, IP-10, MCP-1, MIP-1A, MIP-1B, PDGF, TNF-α, and VEGF [109].