University of Michigan students walk around campus in Ann Arbor on Oct. 20, 2020.

University of Michigan students walk around campus in Ann Arbor on Oct. 20.

WASHINGTON — A group of scientists that ran U.S. clinical trials for coronavirus vaccines last year is launching an ambitious new study to look at their effectiveness, including whether vaccinated people can become infected with COVID-19 and spread it to others.

The trials will also look at whether new variants of the coronavirus are able to infect and spread among vaccinated people more than the original virus.

The randomized, controlled study began enrolling more than 12,000 college students between 18 and 26 years old last week at more than 20 universities across the country. The students will self-swab their noses every day for four months to test for COVID-19 after receiving Moderna’s vaccine.

College students were chosen because “young people have a lot of asymptomatic infection, and that’s what we’re studying,” said Dr. Larry Corey, leading investigator of the COVID-19 Prevention Network’s operations program headquartered at Fred Hutchinson Cancer Research Center.

Asymptomatic spread is a particular problem on campuses, Corey said. “It’s a problem and a high incidence among college age students. They live in dormitories and have roommates.”

The clinical trial will also rely on apps that will allow students to submit “e-diary” entries on any symptoms they experience, document possible exposure to the virus, and track their specimens sent for lab testing.

The study, funded by the National Institute of Allergy and Infectious Diseases, will also collect information on a total of 25,000 close contacts for those enrolled in the study, allowing scientists to trace quickly any spread of the virus from the vaccinated participants.

Audrey Pettifor, a co-principal investigator leading the new trial and a professor of epidemiology at the Gillings School of Global Public Health at University of North Carolina at Chapel Hill, said that the scope of the study will provide a vast amount of real world data.

“Having nasal swabs every day for four months is going to provide a lot of data on what viral load looks like in people who are vaccinated,” she said.

Last year, advanced clinical trials that tested the safety and effectiveness of coronavirus vaccines did not examine whether vaccinated people had a-symptomatic infections. Instead, the trials only tested whether participants reported mild, moderate or severe symptoms of COVID-19.

Since vaccines have become available to the public, smaller studies have emerged indicating that vaccinated people are largely protected against infection.

But the studies that have been published so far have been “observational,” and not large in scope or data-driven, Pettifor said.

“I think we’re really hopeful that this will confirm what the observational studies are showing,” Pettifor said.

“We’re really hopeful that the study will show that, if you’re vaccinated, there’s a very low risk of acquiring infection and spreading it to other people. But we don’t know that,” she said. “That’s why we’re doing the trial. And we’re nervous about what the variants will mean for the efficacy of the vaccines.”

Corey, who oversaw the vaccine trials last year, said that the new study is the “only trial of its kind” and will help policymakers make decisions with greater confidence.

“When people get swabbed after they’ve been vaccinated, they seem to have a lower frequency of infection. That’s giving us hints that the vaccine is capable of doing that. But it’s not giving you enough data to tell you how to make policy guidelines,” Corey said.

“We know with all infectious diseases — and we certainly know with SARS-CoV-2 — that most of the transmission occurs within the first three to five days,” Corey said, using the technical term for the novel coronavirus. “So we’ll also know among those who got infected whether they transmitted during that period of time.”

Universities participating in the trial include University of Washington, University of North Carolina, University of Florida at Gainesville, University of Kentucky, University of California at San Diego and Texas A&M — College Station.

Organizers of the clinical trial had hoped to incentivize college students to enroll with early access to the vaccine. Accelerated expanded access to vaccines across the country is a welcome development, Pettifor said, but might make it more difficult to enroll the number of students needed.

Corey said that the start of the trial was “fortuitous” at a time when variants are spreading throughout the United States. The trial could become an opportunity to gain critical data on how they spread.

“It’s really important at the population level to understand transmission, and that’s why we have different thresholds for herd immunity,” Pettifor said.

“That’s what we need to understand,” she added, “that in the face of these variants, what is the level of vaccination that’s going to be needed at a population level to keep this infection under control?”