Analysis of cytokine levels in the serum of patients with COVID-19 in a study in China showed that the levels of IL-6, IL-1β, IL-7, IL-8, IL-9, IL-10, IL-2, FGF, G-CSF, GM-CSF, IFN-γ, IP-10, MCP-1, MIP-1α, MIP-1β, RANTES, PDGF, TNF-a, and VEGF are elevated compared to healthy controls. Here, CCL4 is linked to COVID-19.