Although the relevance of IL-33 in the Th17/Treg cell imbalance associated with COVID-19 has not been reported, we suggest that IL-33 is likely to similarly induce an imbalance in the Th cell subsets locally in the lung and also systemically in a DC-dependent manner, resulting in irreversible hyperimmune damage and inflammatory responses. The gene discussed is IL33; the disease is COVID-19.