Sex and Gender Fail to be Factored into Most COVID-19 Clinical Studies

Analysis Shows Only 4% of COVID Studies Plan to Address Sex/Gender When Considering Results

Although COVID-19 affects men and women differently, most current clinical studies of SARS-CoV-2 and COVID-19 make no mention of sex and gender. Indeed, only a fraction (4%) of such studies explicitly plan to address sex/gender when considering results, concludes a new analysis of 4,420 studies registered with

According to the analysis, 21% of the studies take sex/gender into account when selecting participants while 5.4% go as far as planning to have sex-matched or representative subgroups and samples. An article based on the analysis was published in Nature Communications and was conducted by researchers at Nijmegen’s Radboud University Medical Center, Aarhus University, University of Copenhagen, and University of Bielefeld.

Men are more vulnerable to a severe course of COVID-19; more men are hospitalized and more men die from the effects of the virus. The consequence of the difference may be that men and women need different therapies. At the same time, gender is connected to the risk of infection, for example because women more commonly are employed in positions with client or customer contact, or as caregivers, increasing the risk of exposure. This calls for attention to both dimensions when conducting clinical trials and planning public health measures.

According to one of the article’s coauthors, Sabine Oertelt-Prigione from Radboud University and at the Medical School of the University of Bielefeld, the lack of consideration of sex and gender is problematic: “We have seen from the beginning that the disease does not have an identical course for women and men. The differences in rates of hospitalization and death point to this. This means that our care, such as medicines or other interventions, could also have a different outcome depending on whether the patient is a woman or a man.”

The analysis found that 124 studies (2.8%) focused solely on one sex, with 100 recruiting only female participants and 24 only male ones. Female-only studies mostly focused on the relation between COVID-19 and pregnancy outcomes.

A reason for not including data on sex and gender may be that the studies are conducted under high time pressure. According to Oertelt-Prigione, “Researchers are sometimes worried that analyzing sex differences in a study might mean more participants and longer recruitment times to reach their targets. Especially in the early phases of the pandemic, they were working under lots of time pressure. …We increasingly see that men and women respond differently to pharmacological interventions. Ignoring this in trials might lead to serious, unwanted side effects later.”

Edited by Gary Cramer