COVID-19 vaccines appear to do a great job of protecting people from severe disease, hospitalization and death.

But a key question – with implications for long-term control of the pandemic – remains: Can vaccinated people get mild or asymptomatic infections and pass the virus on to others?

Scientists at the Fred Hutchinson Cancer Research Center and several other institutions now hope to find the answer with the help of thousands of college students across the country – including at the University of Washington.

A major study announced Friday, called Prevent COVID U, aims to enroll 12,000 students at 21 colleges and universities and follow them for five months. Half the young people, ages 18 to 26, will get the Moderna vaccine right away. The rest will get the shots starting four months later.

All of the participants will keep electronic diaries, swab their noses every day and provide periodic blood samples. The idea is to detect even low levels of the novel coronavirus as soon as they appear and compare the vaccinated and unvaccinated groups.

More than 25,000 of the participants’ roommates, friends and other close contacts are also being asked to pitch in by answering weekly questionnaires and taking daily nasal swabs to see if they pick up the virus.

“This kind of study has never really been done before,” said Dr. Helen Chu, the UW Medicine virologist who will be recruiting 600 to 1,000 students locally and analyzing their specimens.

The outcome will help determine when life can truly get back to normal – including whether vaccinated people need to keep wearing masks, said Dr. Larry Corey, Fred Hutch virologist and co-director of the national COVID-19 vaccine trials network, which is coordinating the work.

“It affects travel behavior. It affects stadium behavior, large gatherings, contact with people outside your family,” he said. “There’s also the sense of personal responsibility about whether you can inadvertently transmit a virus that can be very harmful to others.”

The more effective the vaccines are at eliminating asymptomatic spread, the sooner the virus will be brought under control. And the project is well timed to yield better understanding of the new variants that are spreading rapidly and may be less susceptible to existing vaccines, Corey added.

College campuses provide an ideal setting for this type of study, said Chu. Students often live in dorms and other congregate settings, and are more likely to socialize than older adults. They’re at high risk of contracting the novel coronavirus and spreading it to others, even though their own symptoms may be mild or nonexistent.

The UW hasn’t returned to in-person learning on a large scale, but it has already experienced multiple COVID-19 outbreaks among young people living in dorms and on Greek Row.

A tracking survey by the New York Times counted more than 397,000 infections on college campuses that reopened in the fall of 2020. The majority of new infections now occur in younger people, a trend that began last spring and has intensified as more older people get vaccinated.

Like all research studies, it’s entirely voluntary, but Corey hopes support will be high. Most young people aren’t yet eligible for the vaccine, so getting the shots might provide an incentive for some. Volunteers will also be eligible for up to $900 in compensation.

However, those randomly assigned to the control group won’t get their first vaccine until late July. That might be a disincentive since President Joseph Biden has called for states to open their vaccine queues to everyone 16 and older by May 1.

“We are looking for people who want to help answer this question and find it important enough that they will make (some sacrifices),” Corey said.

Among those who stick with the study, daily sampling will provide an opportunity to track infections in unprecedented detail as they unfold and help fill in gaps about the virus and its proliferation. Genetic sequencing will help trace infection pathways and identify viral variants.

There are already several strong hints that vaccines can prevent asymptomatic infection and viral transmission, said Angela Rasmussen, a Seattle-based virologist with Georgetown University’s Center for Global Health Science and Security who is not involved in the new project.

Israel, which has the world’s highest vaccine coverage, has seen a sustained drop in transmission, though strict lockdowns might also have played a role, she said. An analysis of health workers in the U.K. suggested a similar effect – but no analyses have yet been performed of the scale and type of Prevent COVID U.

“I think it’s fantastic,” Rasmussen said. “It’s really nice to see a big study like this that will directly address the question.”

Though specific to the Moderna vaccine, the results will probably be somewhat generalizable to other vaccines, she added. Pfizer’s uses the same messenger RNA technology, and all of the vaccines rely on the same general approach of targeting the spike protein the virus uses to attach to and infect human cells.

The study is funded with about $90 million from the National Institutes of Allergy and Infectious Disease. The other institutions involved are the University of North Carolina at Chapel Hill, Harvard Medical School, Beth Israel Deaconess Medical Center and University of Nebraska Medical Center.

The 21 college campuses have mostly reopened to in-person learning, and were chosen to reflect a diverse student population and different geographic areas where different variants may be circulating, Corey said. They range from tiny Texas A&M University Kingsville to the universities of Florida, Maryland, Kentucky and Arizona. Morehouse School of Medicine in Atlanta and Charles R. Drew University of Medicine and Science are among the historically Black schools included.

The first students were vaccinated Thursday at the University of Colorado, Boulder.

Chu expects to begin recruiting at UW within days, and she’s hopeful the results will show the vaccine can prevent most “silent” infections.

“It’s probably not going to get it down to zero,” she said. “I do think vaccination will reduce asymptomatic infection significantly – but this is the trial that will prove it.”

More information is available at preventcovidu.org.