IL-6, IL-8, IL-10, and TNF-α were increased in severe cases of COVID-19 while IFN-α, IL-1β, IL-4, and IL-15 were enriched in mild cases (Del Valle et al., 2020; Huang et al., 2020; Ruan et al., 2020; Garcia-Beltran et al., 2021). Here, IL4 is linked to COVID-19.