IL9 and COVID-19: The ratios of IFN-γ/IL-4, IL-12/IL-4, IFN- γ/IL-9, TNF-α/IL-4, IFN- γ/IL-5 and IL-12/IL-9 were lower ((≈30-, 11-, 8, 4-, 4-, and 3- fold differences respectively) in COVID-19 ICU patients as compared to HC subjects.