The ratios of IL-12/IL-4, IL-12/IL-10, IL-12/IL-5, IL-12/IL-9, IL-2/IL-10, and IL-2/IL-9 were substantially higher in COVID-19 ICU patients compared with HC subjects (≈5660-, 5333-, 2100-, 600-, 69-, and 24-fold differences, respectively). Here, IL9 is linked to COVID-19.