Immune mediators such as inflammatory cytokines and chemokines, including interleukins (IL-1β; IL-6, IL-7, IL-8, IL-9, IL-10), induced protein 10 (IP10), C-reactive protein, tumor necrosis factor (TNF-α), monocyte chemoattracting protein 1 (MCP-1), are significantly elevated in patients with COVID-19. Here, IL9 is linked to COVID-19.