For instance, the ratios of IL-2/IL-5, IL-2/IL-10, IL-2/IL-9, IL-6/IL-5, IL-6/IL-10 and IL-6/IL-9 were considerably higher in COVID-19 ICU patients as compared to HC subjects (≈8571-, 4800-, 4444-, 378-, 521-, and 172-fold differences respectively). This evidence concerns the gene IL9 and COVID-19.