Interferon: the invisible link between COVID-19 and BCGitis female protection?

Gender distribution of COVID-19 severity is unbalanced. Higher mortality rates are reported in men (60-70% deaths in men). We reviewed 243 BCGitis cases reported in the literature. The M/F ratio in BCGitis is 49:1 and is not fully explained by the higher incidence of bladder cancer among males, neither by anatomical reasons. We discuss the M/F ratio in BCGitis in the light of immune system differences among different genders, with a focus on interferon response (higher in females).