Do COVID-19 vaccines stop transmission? Top scientists are now recruiting thousands of college students to find out

• A study began on Thursday to see how well Moderna's COVID-19 vaccine stops the spread of the virus.
• Scientists plan to recruit 12,000 college students across 21 campuses for the clinical trial.
• They hope it will tell us how well vaccines prevent asymptomatic infections and stop transmission.

Scientists launched an ambitious study on Thursday to figure out how well Moderna's coronavirus vaccine prevents people from spreading the virus to others.

We know Moderna's shot is very good at preventing people from becoming sick with the disease. But we don't know whether vaccinated people could still harbor the virus - perhaps without showing symptoms - and pass it on to others.

To figure that out, researchers plan to recruit 12,000 students across 21 college campuses, including the University of Maryland, Texas A&M, and Indiana University. People interested in participating can register at PreventCOVIDU.org.

"We hope that within the next five or so months we'll be able to answer the very important question about whether vaccinated people get infected asymptomatically, and if they do, do they transmit the infection to others," Dr. Anthony Fauci, the nation's top infectious-disease expert, said Friday at a White House COVID-19 task force briefing.

Half of the volunteers will receive Moderna's coronavirus vaccine right away, while the other half will get their shots four months later. While compensation varies, some student volunteers can get almost $1,000 to participate.

Researchers will track the volunteers to see how well vaccination prevents coronavirus infections, including asymptomatic cases, and reduces viral transmission among their close contacts. Every day, volunteers will take swabs of their nose, place them in a bar-coded vial, and drop them off at collection boxes. The samples will be sent to laboratories to be checked for the coronavirus.

The trial will hopefully deliver results in September, Dr. Larry Corey, a virologist at the Fred Hutchinson Cancer Research Center, said in an interview. Corey has spearheaded the trial, helping to design the study and advocating for funding since November, Insider previously reported.

Scientists zeroed in on colleges as ideal places to carry out this research. One nationwide study found nearly 400,000 COVID-19 cases on more than 1,800 campuses since they reopened last fall.

"High-density housing, the impulse to socialize and less fear of severe disease in young people are all factors that contribute to the high burden of SARS-CoV-2 infection on college campuses," Holly Janes, a professor at Fred Hutch and study leader, said in a statement.

Answering one of the largest unknowns about COVID-19 vaccines

The first COVID-19 shots, from Moderna and Pfizer, appeared to be overwhelmingly effective in data first released in November. The primary goal of those studies was to look at symptomatic COVID-19 cases, partly because it was an easier metric to track.

Those studies enrolled tens of thousands of people and showed that the shots were incredibly effective at preventing people from developing symptomatic COVID-19. In Moderna's study, the two-dose vaccine was 94% effective at preventing COVID-19 cases when compared with people who got placebo shots.

The initial studies left open the possibility that immunized people could still be vulnerable to spreading the virus, potentially as unknowing asymptomatic carriers.

"It's definitely an unknown," Corey said. "In my circles, it's been pretty well delineated that you don't know whether you can asymptomatically transmit, and therefore you should still be careful around unvaccinated persons."

That uncertainty has been a key reason that public-health officials have urged people, including vaccinated individuals, to continue wearing masks and socially distancing.

While real-world data has given hopeful signs that the shots can reduce infections, this study attempts to answer that question in a rigorous manner.

A delay in funding means the study could take longer to find an answer

While the original goal was to start this research in January, it took longer than expected to secure federal funding to run the study, The Wall Street Journal's Peter Loftus reported in December. The emergence of variants, the ramping up of the vaccine supply, and the recognition that the virus would likely become endemic helped move the study proposal along, Corey said.

The US National Institutes of Health's infectious-disease unit is funding the trial, and Corey said the funding was in the "high tens of millions."

The delay may make it harder for the trial to generate a timely answer. The US government is pushing to make all American adults eligible for vaccines by May 1. For volunteers who are randomly selected to receive the shot four months later, that means waiting until July.

Corey hopes a sense of altruism will persuade volunteers to stick with the trial

The five-month follow-up period will also bleed into the summer, when some volunteers are likely to leave campuses. That could make it harder to track or keep people in the study. Corey said the trial sites would look to recruit students who want to stay on campus or live nearby, and he hopes a sense of altruism will retain volunteers, even if they can access a vaccine outside the trial.

"The reason to volunteer is to help the country answer this question for themselves and their parents and their relatives and their communities," Corey said.

The biggest obstacle, securing funding to run the trial, has been overcome. The research could provide the best data yet to answer a question that will inform how quickly people can get back to a world without masking and social distancing.

And in the process, some college kids can get the vaccine now and be paid to help answer this question. Compensation will vary by location to account for cost-of-living differences, and volunteers can make as much as $947 if they fully participate, a Fred Hutchinson representative said.