How inclusive were UK-based randomised controlled trials of COVID-19 vaccines? A systematic review investigating enrolment of Black adults and adult ethnic minorities

Abstract

Objectives: To establish if Black adults and adult ethnic minorities, defined as any group except White British, were represented in UK-based COVID-19 vaccination randomised controlled trials (RCTs) when compared to corresponding UK population proportions, based on 2011 census data.

Design: Systematic review of COVID-19 Randomised Controlled Vaccine Trials SETTING: United Kingdom PARTICIPANTS: Randomised Controlled Trials of COVID-19 vaccines conducted in the UK were systematically reviewed following PRISMA guidelines. MeSH terms included "Covid-19 vaccine", "Ad26COVS1", and "BNT162 Vaccine" with keywords such as [covishield OR coronavac OR Vaxzevria OR NVX-CoV2373] also used. Studies that provided (A) participant demographics and (B) full eligibility criteria were included. The following key data was extracted for analysis: number of participants analysed, number of Black adults and number of adult minority ethnicity participants.

Primary and secondary outcome measures: The primary outcome is the mean percentage of Black adults randomised to COVID-19 vaccine trials deemed eligible within this review. The secondary outcome is the mean percentage of adult ethnic minorities randomised.

Results: The final review included 7 papers and a total of 87 sets of data collated from trial sites across the UK. The standard mean percentage of Black adults included in the trials (0.59%, 95% CI: 0.13% - 1.05%) was significantly lower compared to the recorded Black adult population (2.67%) indicating that they were under-served in UK based COVID-19 vaccine RCTs (p < 0.001). Adult ethnic minority presence (8.94%, 95% CI: 2.07% - 15.80%) was also lower than census data (16.30%), indicating they were also under-served (p = 0.039).

Conclusion: The findings show that COVID-19 vaccine trials failed to adequately randomise proportionate numbers of Black adults and adult minority ethnicities. More inclusive practices must be developed and implemented in the recruitment of underserved groups to understand the true impact of COVID-19.

Fig. 1

PRISMA flowchart of the study selection process

Fig. 2

Plot with squares depicting the inclusivity (as a percentage) of Black adults across all 7 studies alongside a diamond depicting overall mean (with ends representing 95% CI) in comparison to the proportion they make up within the UK population (as represented by the line at 2.67%). NB: “No. black adults” denotes the number of Black adults enrolled in each study

Fig. 3

Plot with squares depicting the inclusivity of black adults and ethnic minorities (as a percentage) across all 7 studies alongside overall mean (with ends representing 95% CI), in comparison to the general population of the UK (as represented by the line at 16.30%)

Fig. 4

Number of reported datasets per region. *denotes where location was not able to be mapped