In a recent rapid systematic review, Leisman DE et al. compared the maximum levels of several inflammatory biomarkers (TNFα, IL-8, IL-1β, IL-10, IL-2, IL-4, soluble IL-2 receptor, IFNγ, CRP, ferritin, fibrinogen, D-dimer, LDH, ESR, albumin, procalcitonin, total bilirubin, lymphocyte count, and platelet count) between COVID-19-induced CRS and three other systemic inflammatory conditions: sepsis, non-COVID-19-related ARDS, and non-COVID-19-induced CRS [21]. This evidence concerns the gene IL4 and COVID-19.