Given that the risk of developing severe symptoms in COVID-19 is greater in older men than in older women [37], and since we showed signs of defective IL-10 signaling in frail men, we speculate that defective downstream IL-10 -STAT3 signaling contributes to the severity of infectious diseases such as COVID-19 due to the reduced immune regulatory function of IL-10. The gene discussed is STAT3; the disease is infectious disease.