Mortality in COVID-19: Further Evidence for a Sex-Based Difference in the OpenSAFELY Study.

Although COVID-19 death rates are lower in women compared to men, it is not clear whether this difference in mortality is due to sex (biological) based factors, comorbidities that differ in men and women, or gender influences. New evidence supports a sex-based difference in COVID-19 mortality. Data from the OpenSAFELY cohort study in 17 million adult patients in England demonstrate that COVID-19-related deaths were associated with male sex (hazard ratio 1.59; 95% confidence interval 1.53-1.65) when fully adjusted for age, low income, smoking, pre-existing diseases, and ethnicity. Women have stronger innate and adaptive responses to infection. It is hypothesized that biological differences in the immune system may have a role in the sex-based difference in mortality from COVID-19. The results of OpenSAFELY demonstrate the importance of collection and analysis of sex-disaggregated data in research and public surveillance.