IL2 and COVID-19: For immune cell signaling responses to IFNα/IL-2/IL-4/IL-6 stimulation, we also observed a negative correlation with disease severity for the pSTAT4/5/6 signals in both adaptive and innate immune cells (Figures 4C and S9C), suggestive of an impaired signaling response to IFN and cytokines in those individuals with more severe COVID-19.