IL4 and COVID-19: ICU patients, whose sera were collected in the acute phase of the disease, showed a sustained production of pro-inflammatory mediators, among which IL-6, IL-17A, IL-12p70, IL-1beta, IL-4, IL-5 and IL-13, all associated with the “cytokine storm” observed in very severe COVID-19 patients, were the most abundantly detected (Figure 2A).