Then, the cytokines (including CRP, Ferritin, IL-6, TNF-α, GM-CSF, IP-10, and MCP1α/1β) in the serum of severe patients with COVID-19 were higher than that in the mild patients with COVID-19, while the number of T and NK cells decreased and the number of neutrophils increased. Here, CXCL10 is linked to COVID-19.