SASKATOON -- Scientists from across the U.S. and Puerto Rico are urging for more diversity in vaccine clinical trials after their new study exposed a decade’s worth of disparity from 2011 to 2020, and could have impacted vaccination rates among minorities.

The research, published Friday in medical journal JAMA Network Open, found many U.S.-based clinical trials failed to report demographic information -- and the ones that did frequently underrepresented Black people, Indigenous peoples, Latinxs, and people over the age of 65.

"This collaborative work highlights a problem that's plagued the scientific community for too long,” Dr. Steve Pergam, one of the authors of the study said in a press release.

The team combed through 230 U.S.-based vaccine trials of all phases, with nearly 220,000 participants from July 2011 through June 2020.

Although Asian and Pacific Islanders were equitably represented in vaccine trials compared to the U.S. population, white people and adult women tended to be overrepresented.

In the paper, the authors wrote, “when people with diverse backgrounds are not adequately represented, treatments shown to be effective in trials may not be generalizable to or effective for all populations.”

“Furthermore, because of previous experience with exclusion and maltreatment, vaccine hesitancy and lack of trust in the medical establishment may be more prevalent across minority groups, making inclusion even more important.”

Dr. Julie Silver, one of the senior authors on the study and an associate professor at Harvard Medical School, called for immediate action.

"Going forward, we need to ensure all vaccine studies report demographic information,” she said in the release.

Researchers said many studies didn’t comply with policies and guidance on reporting demographic data, and this was in spite of recommendations by the National Institutes of Health and the Food and Drug Administration.

“And missing data may be important in the context of understanding health disparities, such as social determinants of health (e.g., socioeconomic barriers), implicit bias, and an increased burden of comorbidities,” the authors said.


The non-profit organization Kaiser Family Foundation, which wasn’t involved with the study but provides in-depth information on key health policy, laid out why people of colour might not be represented in trials.

Last month, their analysis found it was a combination of inadequate outreach efforts, lack of awareness or information, and structural access challenges. People of colour’s lingering feelings of historical mistreatment by the medical community also played a huge role, as did ongoing bias against them in the health-care system.

The team behind the latest study noted those facing greater burden from infectious diseases should receive equitable inclusion in vaccine trials.

Pergam, associate professor in the vaccine and infectious disease division at Fred Hutchinson Cancer Research Center in Seattle, Wash., said the COVID-19 pandemic a “painful reminder” of how the virus has disproportionately devastated Black, Indigenous and people of colour and older people in long-term care facilities.

In the study’s press release, he pointed to efforts by vaccine developers as examples of how it is possible to strive to further diversify trial participants.

“The diversity seen in COVID-19 vaccine trials demonstrate we can do this, but we need to assure future studies focus not just on rapid enrollment but also on inclusion,” Pergam said.

Although there have been some efforts to diversify vaccine trials, experts say there’s still a ways to go. Throughout COVID-19 vaccine development, researchers have been regularly struggling with underrepresenting certain racial groups within vaccine trials.

"Vaccine hesitancy and a lack of understanding about safety is a major challenge we're facing with COVID-19," Dr. Michele Andrasik, a senior staff scientist at Fred Hutch and study co-author, said.

"By improving enrollment diversity, we can better engage these underrepresented groups early in the trials stage and address the education and trust issues,” she added.

Engagement with racial groups is critical as vaccines are rolled out across the world. Last year, research from Britain suggested people from ethnic minority backgrounds or with lower incomes are less likely to take the coronavirus vaccine.

To tackle the problem of enrolling more minorities in vaccine trials, the U.S.-based National Academies of Sciences, Engineering, and Medicine recently set up a committee dedicated to improving the representation of women and underrepresented minorities in clinical trials and research.