Shift from Th2 to Th1 response is characterized by increasing levels of IL-1β, IL-2, IL-12, TNFα, and IFNγ in plasma (48), but these cytokines, except for TNFα, were only increased in mild COVID-19, whereas in severe and critical COVID-19 only TNFα was significantly increased, likely contributing to the cytokine storm (49). This evidence concerns the gene IL2 and COVID-19.