Do COVID vaccines prevent transmission? CU Boulder kicks off national trial

At 10:25 a.m. Thursday, CU Boulder senior Olivia Parsons became the first participant to receive vaccination in a national study aimed at answering a critical question in the fight against COVID-19: Does the Moderna shot prevent people from spreading the virus?

“Honestly, I felt like it was my civic duty to participate,” said Parsons, 22, moments after a doctor at the Clinical and Translational Research Center (CTRC) on the Boulder campus administered her first Moderna vaccine. “It’s an honor.”

Parsons is among 12,000 students, ages 18 to 26, from 21 universities who will participate in PreventCOVIDU, a five-month, federally-funded study led by the COVID-19 Prevention Network (CoVPN) at Fred Hutchinson Cancer Research Center in Seattle.

CU Boulder was the first site to roll it out, with study leaders on Thursday vaccinating 11 of the roughly 700 CU Boulder student volunteers who will ultimately participate.

“We know from previous trials that this vaccine protects those who are vaccinated from moderate and severe disease, hospitalization and death. The question now is: Does it also protect others?” said Integrative Physiology Professor and CTRC Director Christopher DeSouza, co-principal investigator for the CU Boulder site.  

National study leader Dr. Larry Corey, principal investigator of CoVPN’s operations program, added that the purpose of this trial is to tell us whether a person can become infected after they’ve been vaccinated and if the vaccine will stop the virus from spreading from person-to-person.

To find out, researchers will vaccinate half the students right away, while vaccinating the other half four months later. Volunteers will then be asked to swab their nose—typically the site of first infection—every day, get tested twice weekly via CU Boulder’s on-campus saliva monitoring program and complete daily questionnaires about symptoms via an app on their phone. They’ll also have their blood drawn periodically.

Collectively, all this data will enable researchers to capture infections in real time and track the viral load, or the amount of viral particles present in an infected individual, over the course of an infection.

Researchers will also track 25,500 close contacts of participants nationwide.

If a study participant tests positive, close contacts will be asked to collect daily nasal swabs for 14 days as well as blood samples to determine if they, too, get infected.

Each student participant will be followed for five months, with the vast trove of resulting data providing new insight into how well the vaccine prevents transmission—including asymptomatic transmission—of SARS CoV-2, the virus that causes COVID-19.

“Until we know how much vaccination protects you from infecting others, it is hard to know how much to relax restrictions and fully reopen things,” said co-principal investigator Dr. Brian Stauffer, medical director of the Clinical and Translational Research Center at CU Boulder and chief of cardiology at Denver Health Medical Center.

The researchers say that while the study centers on college students, the findings will be highly applicable to the population at large.

They hope to report results prior to fall 2021.

Although only the Moderna vaccine will be used in the trial, Corey said the results will apply equally well to the Pfizer-BioNTech vaccine, which uses a similar technology (called mRNA) to train the body’s immune system to recognize and attack SARS-CoV-2.

The findings will be key to informing science-based decisions about mask use and social distancing post-vaccination. The results can also inform college administrators as they craft plans for returning to campus in the fall, said DeSouza.

Infection rates can be high on college campuses due to students living in close quarters, and many who are infected have no symptoms. Therefore, a campus provides a “model setting” for studying transmission—particularly asymptomatic transmission, he said.

A nationwide survey found that more than 397,000 infections were counted at 1,800-plus universities after reopening in the fall of 2020. Two separate studies last October reported that SARS-CoV-2 infections among young people aged 18-22 increased 55% nationally between August and September 2020. Between June and August 2020, young people aged 20-29 had the highest incidence of SARS-CoV-2 infection in the United States, accounting for more than 20% of cases.Because CU Boulder already requires students living in the residence halls to participate weekly in saliva surveillance for SARS CoV-2, the campus was well-positioned to be an early participant in the trial, said DeSouza.

In the coming four to six weeks, the national and CU Boulder teams will continue to recruit participants. If students in the phase of the study designated for a delayed vaccine have an opportunity to be vaccinated before that, they are not prohibited from doing so but it is hoped that they will complete the study.

Study volunteer Chase Willie, a senior media design major at CU Boulder, said Thursday’s jab in the arm felt like a dose of much-needed relief.

“I miss not being scared - just being able to go out and interact with people and laugh and have fun and not worry that I am going to bring something back to my parents,” Willie said. “I know this is just the first shot, but it feels like the beginning of something good.”

The trial is funded by the Federal COVID-19 Response Program and the National Institute of Allergy and Infectious Diseases. The COVID-19 Prevention Network (CoVPN) was formed by the National Institute of Allergy and Infectious Disease (NIAID) at the US National Institutes of Health.

To inquire about participating, email covpnstudy@colorado.edu.