IL9 and periodontitis: In patients with COVID-19 hospitalized in intensive care units, elevated serum levels of IL-1β, IL-7, IL10, IL-17, IL-2, IL-9, Th17, IFN-γ, GM-CSF, G-CSF, IL-8, TNF-α, MIP1B, MCP1, MIP1A, and IP10 were observed, suggesting that the relation between periodontitis and COVID-19 may be established [32].