Some type 2 cytokines (IL-4, IL-9, IL-13, etc.)have inhibitory effects on the production of proinflammatory cytokines (IL-1β, IL-6, TNF-α, etc.), the overactivation of which have been proposed as a potential key mechanism of protection against COVID-19 to some extent (Liu et al., 2020). The gene discussed is IL9; the disease is COVID-19.