March 29, 2021

New COVID-19 vaccines have been proven to keep people from getting sick. But no one knows yet whether they will keep those who have been vaccinated from spreading the coronavirus to others.

That information may come from the Prevent COVID U study conducted by the COVID-19 Prevention Network (CoVPN) at 22 universities across the United States. The University of North Carolina at Chapel Hill announced today it hopes to enroll about 600 students willing to swab their noses every day over the course of the four-month trial.

Dr. Audrey Pettifor

Dr. Audrey Pettifor

“We already know that vaccination can prevent serious COVID-19 disease, but we do not know if the vaccine will prevent the virus from shedding from the nose and mouth and infecting others,” said Audrey Pettifor, PhD, professor of epidemiology at the UNC Gillings School of Global Public Health and co-principal investigator of the nationwide study. “That is what we are testing in this study.”

Early in the pandemic, Pettifor, an HIV/AIDS researcher, began applying her experience in HIV prevention to identify ways to control the coronavirus. Her new focus now includes serving as a leader of the Prevent COVID U study.

Principal investigators in charge of getting the study up and running at UNC-Chapel Hill are Sylvia Becker-Dreps, MD, a family medicine physician and associate professor of epidemiology at the Gillings School, and Nadja Vielot, PhD, an epidemiologist and assistant professor of family medicine at the UNC School of Medicine.

The study builds on clinical trials that tested the ability of vaccines to prevent severe COVID-19 symptoms. It was unknown whether vaccinated people could become infected without showing symptoms and unwittingly spread the virus.

More than 12,000 university students, who will be paid, will get the Moderna COVID-19 vaccine to help researchers learn if vaccinated people can still be infected with SARS-CoV-2, the virus that causes COVID-19, and if they are able to spread the virus to other people.

The answers to these questions could lead to science-based decisions for when it might be safe to have large gatherings and ease off wearing masks post-vaccination, according to study leader Larry Corey, MD, principal investigator of CoVPN’s operations program and professor at the Fred Hutchinson Cancer Research Center, where the network is headquartered.

Prevent COVID U opened initial study sites on March 25, and results are expected to be ready before the fall semester begins.

UNC-Chapel Hill students ages 18-26 years old are eligible to participate in the study if they have not had COVID-19 and plan to be around the Chapel Hill-Carrboro area this summer. Participants will be asked to follow the university’s COVID-19 testing program and get tested twice a week.

It is a two-arm trial, meaning there are two possible treatment assignments — half of the students will be randomly selected to receive the vaccine right away at enrollment, while the other half will get the vaccine four months later. All participants will know which arm of the trial they are in at enrollment, and all will ultimately receive the vaccine.

Throughout the study period, participants will complete questionnaires via an eDiary app, swab their nose daily for COVID-19 infection and provide periodic blood samples.

The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health (NIH), formed the COVID-19 Prevention Network to conduct large studies of COVID-19 vaccines and treatments. The NIH is paying for the study.

Ideal population

College students are an ideal population to participate because large numbers of COVID-19 cases have been reported on numerous college campuses throughout the U.S. A nationwide survey found that more than 535,000 infections have been counted at universities since the pandemic began.

While there are many populations who have a high risk of COVID-19 infection, young people are particularly at risk for getting and spreading the virus. High-density housing, the impulse to socialize and less fear of severe disease contribute to the high burden of COVID-19 on college campuses, said study designers.

To test the vaccine’s effectiveness to reduce and/or prevent the spread of the virus to others, about 25,500 individuals identified by participants as close contacts (for example, roommates) will also be invited to take part in the trial.

“By participating in this study, UNC-Chapel Hill and its students are contributing to history and should be congratulated for the role they will play in moving us through this pandemic,” said Pettifor.

To learn more about the clinical trial go to Prevent COVID U, or email

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