Researchers seek gender-specific COVID-19 data

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Canadian health experts are encouraging scientists to explore how women and men react differently to treatment for COVID-19 as self-reported data from Canada and the world continue to show that women are reporting the majority of side effects from coronavirus vaccines.

The Institute of Gender and Health, a part of the Canadian Institutes for Health Research, is funding COVID-19 research that takes sex into account. This comes at a time when some sex researchers are criticizing vaccine clinical trials around the world for not yet reporting data on sex-specific responses to COVID-19 vaccines.

Knowing more about how women and men respond to treatment could warrant research about the potential benefits of a lower COVID-19 vaccine dosage for women in the future, said Cara Tannenbaum, scientific director of the Institute of Gender and Health.

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“A one-size-fits-all dose goes counter to the idea of precision-based medicine that we’ve been working toward over the past several years,” said Dr. Tannenbaum, who added that the federal government’s sex and gender-based analysis policy obliges health researchers to address the different needs of women and men. “We would learn so much if we would embrace and study these differences.”

Since the start of the pandemic, researchers have found differences in how men and women contract and react to the novel coronavirus. World data so far indicate that more men exhibit severe symptoms and die of COVID-19 than women, but a recent report from the U.S. Centers for Disease Control and Prevention shows that women tend to display more side effects to COVID-19 vaccines. In Canada, 87 per cent of adverse events after being vaccinated were reported by women. Most of those side effects, such as redness, swelling and dizziness, have been reported to be mild.

Still, some scientists criticize the lack of differentiation between men and women in COVID-19 research. A preprint study from the University of Copenhagen indicated that barely 4 per cent of registered COVID-19 trials published by September, 2020, alluded to sex in their analyses. Some researchers argue the paucity of sex-specific data for COVID-19 treatment is creating major knowledge gaps that will affect the lives of both women and men as the pandemic continues.

Eleanor Fish, Canada Research Chair in Women’s Health and Immunobiology, said that reporting more sex-specific data from vaccine clinical trials could have generated more information about expected side effects, but that the prevalence of side effects would likely have been too small to preclude the rollout of vaccines. A greater value of knowing more about sex-specific responses to the vaccines, she said, could be to help in determining future dosage.

“If there was ever a time to consider dose sparing, I would have thought now would have been the time, and nobody is doing it,” she said. “The question is: By reducing the dose [for women], would you be able to achieve the same efficacy?”

Dr. Fish said that testing and packaging varying vaccine doses for worldwide distribution would probably involve too much time and logistics in pandemic times, when the goal is to distribute safe vaccines as quickly as possible. An opportunity for sex-specific vaccine research, however, still exists, she said.

If regular booster shots for SARS-CoV-2, the virus that causes COVID-19, are eventually required, it could become important to know how to tailor doses to men and women, as well as to vulnerable members of the population such as cancer patients. Continuing sex-specific research could also help inform how men and women react to possible COVID-19 variants.

Not separating data based on sex and underrepresenting women in clinical trials are not new problems in health and medical research. In previous decades, men were considered the norm of clinical trials, while data from women were viewed as confounding because of a higher variability in hormonal levels. Some studies considered pregnant women and even women with child-bearing potential as a “vulnerable population” and excluded them from trials.

But during the SARS outbreak of 2003, the different outcomes of men and women infected with SARS-CoV-1, the predecessor of the virus that causes COVID-19, highlighted a need to take sex into consideration when researching coronavirus presentation and treatment, said Dr. Gavin Oudit, a clinician-scientist in the University of Alberta’s Department of Medicine and the Mazankowski Alberta Heart Institute.

Dr. Oudit was on the team of researchers that first discovered angiotensin-converting enzyme 2 (or ACE2), a receptor on which both SARS-CoV-1 and SARS-CoV-2 bind, in 2000. The enzyme is found in greater concentrations in male blood plasma.

In January, he contributed to one of Canada’s first published papers about sex-specific differences in SARS-CoV-2 response, which indicates that men are more likely to exhibit severe symptoms and die of COVID-19 than women because of immunological and genetic factors. He said he hopes that, in keeping with Canada’s health and gender policy, researchers continue to separate COVID-19 research based on sex moving forward.

“COVID-19 has brought to the forefront the importance of sex and gender research in health outcomes,” Dr. Oudit said.

The paper’s main author, Anissa Viveiros, a PhD candidate at the University of Alberta’s Faculty of Medicine, said she was surprised to be one of the first researchers in Canada to publish a study that examines sex differences in COVID-19 outcomes.

“We need to understand why these biological differences are happening in the first place so that we understand how to target them differently,” she said.

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