IL18 and COVID-19: The highlighted inflammatory mediators released by immune cells include Interferon-α, IFN-γ, Interleukin-1β, IL-6, Interleukin-12, IL-17, Interleukin-18, Interleukin-33, TNF-α and Transforming Growth Factor-β with altered levels associated with various clinical features of COVID-19 (47–49).