IL9 and pneumonia: Compared with the healthy controls, plasma levels of IL-1β, IL1ra, IL-2, IL-4, IL-6, IL-8, IL-7, IL-9, IL-13, IL-15, IL-17, basic FGF, IP-10, MCP-1, MIP-1α, PDGF, VEGF, MIP-1β, TNF-α, and RANTES were significantly elevated in COVID-19-related pneumonia patients, whereas levels of IL-5, IL-10, IL-12, Eotaxin, G-CSF, GM-CSF, and IFN-γ were similar between the healthy control group and COVID-19 patients (Figure S3A).