Vaccine Trials Underrepresent Minority Races, Ethnicities, and Older Populations

Compared with US census data, White individuals and women are overrepresented in clinical trials.

New data elucidates the shortcomings in meeting diversity enrollment targets for United States-based vaccine trials.

Furthermore, the findings suggest a greater need to more equitably represent individuals of underrepresented racial/ethnic groups, women, and people aged ≥65 years of age.

“To enhance enrollment of underrepresented groups, the National Institutes of Health (NIH) Revitalization Act of 1993 mandated appropriate inclusion of women and racial/ethnic minority groups in clinical trials,” wrote the investigators. 

“However, decades later, inclusion has remained persistently low,” they stressed.

Thus, in order to capture current enrollment diversity, a team, led by Laura Flores, College of Allied Health Professions, University of Nebraska Medical Center, conducted a cross-sectional study that examined data from completed US-based vaccine trials ranging from July 1, 2011, through June 30, 2020. 

Assessing Diversity in Vaccine Trials

Flores and colleagues collected all relevant data on race/ethnicity, sex, and age of participants.

For race, the team utilized categories offered by the Office of Management and Budget Standards for the Classification of Federal Data on Race and Ethnicity.

They then compared the percentages of these minority populations with US census data from 2011 and 2018.

“For trials reporting demographic information as percentages only, we computed integer counts of participants by multiplying the percentage in each group by the total number of participants analyzed and rounding to the nearest integer,” they explained.

“In the event that counts of mutually exclusive minority groups did not add to the total number analyzed in the trial, we adjusted counts among the other, unknown, or missing category so the sum of participants in all minority groups matched the total number of participants analyzed in the trial.”

Underrepresentation or Overrepresentation

The investigators analyzed a total of 230 trials and 219,555 participants.

A majority (78.3%) of these studies were randomized trials, included viral vaccinations (69.1%), and represented all trial phases.

Thus, among all adult study participants, 77.9% were White individuals (95% CI, 77.4-78.4), 10.6% were Black or African American individuals (95% CI, 10.2-11.0), and 0.4% identified as American Indian or Alaska Native (95% CI, 0.3-0.5).

Following comparisons with US census data, the investigators noted overrepresentation in White individuals and underrepresenation in the latter races.

Asian individuals represented 5.7% of the entire population of participants (95% CI, 5.5-6.0)—which was considered equally representative compared with data from the US census.

In the few trials (34.4%) reporting ethnicity, Hispanic or Latino representation was low among the participant population (11.6%; 95% CI, 11.1-12.0).

Among those trials that reported race/ethnicity, 48.5% of them did not include American Indian or Alaska Native participants. Further, 60.4% of such trials did not include Hawaiian or Pacific Islander participants.

And finally, the investigators reported that adult trials were composed of more female participants (56.0%), but individuals aged ≥65 years old had low representation (12.1%; 95% CI, 12.0-12.3).

An Opportunity: Final Thoughts

“Our findings suggest that NIH policies on reporting of identified groups has increased over time, but a need to focus such policies beyond reporting to representative enrollment remains,” the investigators wrote.

“Efforts to improve inclusion may help to address vaccine hesitancy, provide education, and counter safety concerns about vaccines by ensuring equitable representation in definitive clinical trials,” they continued.

They also indicated such efforts towards inclusion and diversity may help enhance community engagement and engender trust with minority populations. 

“Future studies are needed to assess whether access to and enrollment in clinical trials will lead to improved vaccination rates in these populations because not all policy changes help improve rates,” Flores and colleagues concluded.

The study, “Assessment of the Inclusion of Racial/Ethnic Minority, Female, and Older Individuals in Vaccine Clinical Trials,” was published online in JAMA Network Open.