Women should not be underrepresented in vaccine clinical trials

By Teresa Bandiola

Photo: https://www.womenshealth.gov/

Differences in gender can often lead to different responses to the same drug or vaccine. Even though both genders are given the same dosage, in most cases, females experience worse adverse effects than males do, such as drowsiness, depression, and heart anomalies.

A good example of this is Zolpidem (Ambien) that is used to treat insomnia. Reports suggest that this drug stays longer in the blood of women. It was found out that blood levels of this drug were 25–33% higher in women than in men. Higher Zolpidem levels can increase drowsiness and the risk of next-day driving impairment that can lead to traffics and accidents. As a result, the US Food and Drug Administration (FDA) in 2013 halved the recommended dosage for women.

In 2018, an oncologist in Switzerland and her colleagues gathered data from chemotherapy trials for esophagogastric cancer. It was found out that females demonstrated significantly higher rates of toxicities than males, primarily gastrointestinal in nature.

Furthermore, even flibanserin (dubbed as “female viagra” drug) that is used to treat low sexual desire in women had sex-based disparities during clinical trial. The drug was initially tested on 23 men and only 2 women. Because of this male-dominated trial, when the drug was released in 2015, adverse effects became more evident in women. Women who took flibanserin while drinking alcohol were at a higher risk of having low blood pressure and temporary loss of consciousness. This is a clear evidence that male-dominated studies can lead to inappropriately medicated women.

The underrepresentation of women in clinical trials can be traced back to 1977 when the US FDA issued a guideline banning women of child-bearing potential from participating in clinical trials, except for life-threatening conditions. This was the result of certain drugs causing serious birth defects (especially the drug thalidomide in the early 1960s). However, in 1993, the US FDA lifted the ban and an act of Congress called on the US National Institutes of Health (NIH) to ensure women’s inclusion in clinical trials.

For the clinical trials of Covid-19 vaccine being developed in the US by Moderna and National Institute of Allergy and Infectious Diseases (NIAID), it is indicated that all sexes are eligible for their study. Female participants of childbearing potential may be enrolled in the study if the participant fulfills all their required criteria, in addition to other requirements such as the age eligibility of 18 years and older.

Including both sexes in experiments is not a waste of time, resources, and efforts. We can not achieve truly personalized healthcare unless we have an equal balance of the genders in clinical trials.


This article first appeared in Daily Guardian newspaper on August 25, 2020 by the same writer.