Data-driven enrollment for COVID-19 vaccine clinical trials

In 2020, a microscopic airborne pathogen stopped the world. The COVID-19 pandemic led to school closures, lockdown orders, mask mandates, and newfound hobbies for thousands of Americans. While many people were stuck at home playing Animal Crossing or baking bread, scientists were working tirelessly to understand the virus and develop a vaccine that would allow us to safely leave our homes. This effort to develop a vaccine necessitated robust clinical trials with many, many volunteers willing to take a chance and receive the COVID-19 vaccine. Luckily for researchers, people were willing and excited to be part of the effort to put a stop to the pandemic.

“My colleagues were enrolling a phase one study for the Moderna vaccine, and they had like 10,000 people sign up on their website. They needed 40 people to enroll,” says Dr. Jim Kublin, senior author of a new article in npj Digital Medicine. While exciting, parsing through that many people to ensure that any vaccine trial had a representative group of participants with different demographics, lifestyles, and potential exposures to COVID-19 was a major challenge. Each trial independently enrolling participants also created to the risk of one participant signing up for multiple trials. To address these problems, Kublin and his colleagues created a centralized volunteer screening registry to support ongoing clinical trials.

The volunteer screening registry had two distinct views: one for the volunteer questionnaire, and the other for administrators to view volunteer information and run analytics to determine which volunteers would be enrolled in the trial. The volunteer questionnaire asked about occupation, residence, community interactions, COVID-19 risks and testing, and other symptoms and health risks for each volunteer. Knowing all this information allowed the administrators to parse and enroll volunteers based on who was at a higher risk of contracting the virus. Once the infrastructure to enroll participants was built, the group launched a massive communications campaign, including an advertisement narrated by Harrison Ford, to raise awareness about the registry and encourage people to volunteer. These efforts were massively successful: the registry launched in July 2020, and more than 600,000 people signed up to volunteer over the next several months.

This cache of volunteers became indispensable to COVID-19 vaccine clinical trials. Hundreds of clinical trial sites accessed the volunteer records in this database, and volunteers were enrolled in six separate clinical trials. Historically, clinical trial participants have been predominantly white with high socioeconomic status, leading to results that do not necessarily represent a broad population. Casting such a wide net with recruitment efforts ultimately increased the diversity of participants in COVID-19 vaccine clinical trials supported by the registry. Volunteers solicited from the registry were more likely to have occupational or behavioral risks (both indicators of lower socioeconomic status) of contracting the virus. The registry also enabled trials to enroll a higher proportion of Black, Indigenous, and People of Color participants compared to ongoing trials that did not enroll from the registry. “When the results are published, people want to see people like themselves in these studies to feel more confident that the results reflect…their demographic,” says Kublin.

These massive vaccine trials led to FDA approval of the first COVID-19 vaccines in 2021, and, eventually, schools and businesses reopened, mask mandates were lifted, and the pandemic hobbies were abandoned. The volunteer screening registry enabled quick clinical trial enrollment of diverse populations that undoubtably aided in vaccine development. In the future, the authors hope that continued investment in collaboration, data standards, and public health communication will promote emergency preparedness within the US government.

This work was supported by funding from the National Institutes of Allergies and Infectious Disease and Oracle Corporation.

Fred Hutch/University of Washington/Seattle Children’s Cancer Consortium Member Dr. Jim Kublin contributed to this research.

Abernethy NF, McCloskey K, Trahey M, Rinn L, Broder G, Andrasik M, Laborde R, McGhan D, Spendolini S, Marimuthu S, Kanzmeier A, Hanes J, Kublin JG. 2025. Rapid development of a registry to accelerate COVID-19 vaccine clinical trials. npj Digit Med. 8(1):251. doi: 10.1038/s41746-025-01666-3.