The NIH added that analysis by sex, as well as race and age, would more likely happen in phase three when the vaccine is administered to more participants. The NIH and Moderna are currently recruiting for phase three, aiming to get 30,000 enrolled.
While there have been recent improvements in recruiting women to participate in clinical trials after a long history of being left out, researchers and clinicians still rarely consider how men and women are impacted differently by a drug or intervention.
The same is true for race and gender. Furthermore, medical schools and residency programs rarely integrate sex differences into education beyond courses about reproductive health.
“Medical training is taught within male-centric literature, and rarely do lectures uncover what’s the difference” between men and women, said Dr. Deborah Bartz, associate gynecologist at Brigham and Women’s Hospital.
Infectious disease specialists with expertise in vaccine development argue that analysis by sex scarcely happens because researchers likely don’t find any differences worth noting. Researchers should and would provide those differences if they come up, said Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases.
Furthermore, even if the data isn’t analyzed by sex, it can be done quite easily for those interested because all the primary data is available, added Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia.
Although sex-based differences haven’t historically been observed during vaccine trials, studies on influenza vaccines do show women respond differently than men. A 2005 study found women had higher immune response rates to both half and full doses compared with men. Reactions from the vaccine like headache and fatigue were significantly higher for women than men. Right now, women and men get the same dose for the flu shot.
But even if the COVID-19 vaccine trials don’t uncover significant differences between men and women, the data should still be analyzed and published, said Brian Prendergast, professor of psychology at the University of Chicago.
“We have inclusion now, but it’s almost like the minimum compliance” is being done, he said. “Perhaps there is a reason to collapse the data together—show me there is no sex difference.”
He also said similar data should always be available for medications. Prendergast along with colleagues recently published a study finding women were more likely to have adverse reactions from FDA-approved drugs when data showed they had differing responses to the drug than men. Drugmakers however aren’t required to put such information on drug labels, so women and men usually receive the same dosage.
Prendergast recommends clinicians prescribe women a lower dose of a drug to be on the safe side and then gradually increase it if symptoms persist.
Sex-based analyses likely still don’t happen because of biases and lack of awareness, said Rosemary Morgan, an assistant scientist at Johns Hopkins Bloomberg School of Public Health.
“Caucasian men have been the ones predominantly in power positions and they have been using themselves as the norm, meaning the male body was given the norm,” she said.
Furthermore, research that does examine differences between men and women is usually done by female researchers, said Dr. Kim Templeton, professor of orthopedic surgery at the University of Kansas and past-president of the American Medical Women’s Association. “We need to bring more male researchers on board,” she said.