Sex differences in severity and mortality from COVID 19: are males more vulnerable?
Coronavirus disease 2019 (COVID 19) has shown high infection and mortality rates all over the world, and despite the global efforts, there is so far no specific therapy available for COVID 19. Interestingly, while the severity and mortality of COVID 19 are higher in males than in females, the underlying molecular mechanisms are unclear. In this review, we explore sex related differences that may be contributing factors to the observed male biased mortality from COVID 19. Males are considered the weaker sex in aspects related to endurance and infection control. Studies show that viral RNA clearance is delayed in males with COVID 19. A recent study has indicated that the testis can harbor coronavirus, and consequently, males show delayed viral clearance. However, the role of testis involvement in COVID 19 severity and mortality needs further research. Males and females show a distinct difference in immune system responses with females eliciting stronger immune responses to pathogens. This difference in immune system responses may be a major contributing factor to viral load, disease severity, and mortality. In addition, differences in sex hormone milieus could also be a determinant of viral infections as estrogen has immunoenhancing effects while testosterone has immunosuppressive effects. The sex specific severity of COVID 19 infections indicates that further research on understanding the sex differences is needed. Inclusion of both males and females in basic research and clinical trials is required to provide critical information on sex related differences that may help to better understand disease outcome and therapy.
Biology of sex differences