The number of COVID-19 cases appears to be comparable between men and women, but the severity of disease and death is two times greater for men than for women. History, including the 1918 influenza pandemic, warned us that male biases in COVID-19 could occur. In this Viewpoint, we focus on biological explanations, with a forward look at why clinicians and biomedical researchers should consider sex as a biological variable that will affect treatment outcomes for COVID-19. There is a long history of not analyzing or reporting differences between women and men in the prophylactic or therapeutic treatment of infectious diseases. We seek to reverse this trend and call on investigators developing and testing therapeutic and prophylactic approaches for COVID-19 to design studies that are inclusive of male versus female differences in drug responses, immunotherapies, vaccines, and nonpharmacological interventions.

Bischof E, Wolfe J, Klein SL. Clinical trials for COVID-19 should include sex as a variable. Journal of Clinical Investigation. 2020;130(7):3350-3352. doi:10.1172/jci139306