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A large-scale clinical trial is underway to answer the million-dollar question about COVID-19: Do the vaccines prevent transmission? Researchers could have that answer within a handful of months, Anthony Fauci, MD, said at a White House news briefing Friday.
“We hope that within the next 5 or so months, we’ll be able answer the very important question about whether vaccinated people get infected asymptomatically,” he said, “and if they do, do they transmit the infection to others.”
The trial, which started Thursday, will involve 12,000 college students across more than 20 universities in the United States. Among them, 6,000 will receive the Moderna vaccine immediately and 6,000 will get it 4 months later.
Participants will complete questionnaires with an electronic diary app and swab their own noses daily, Fauci said. They’ll also provide periodic blood samples. Then, 25,000 of their closest friends and family will be identified.
“The degree of transmission from vaccinated individuals will be determined by the infection rate in the close contacts,” he said.
Preliminary data points to substantially lower rates of transmission among vaccinated people. During a February news briefing, Fauci cited a study from Israel that showed the amount of viral load — or the amount of the COVID-19 virus in someone’s body — is significantly lower if someone gets infected after they’ve been vaccinated, compared with people who get infected and didn’t have the vaccine. A lower viral load means much lower chances of passing the virus to someone else, Fauci says.
The new study will provide data needed to confirm those findings.
During the briefing, Fauci also dismissed the claim from Trump-era CDC Director Robert Redfield, MD, that the virus escaped from a lab in Wuhan, China.
“The issue that would have someone think it’s possible to have escaped from a lab would mean it essentially entered the outside human population already well-adapted to humans, suggesting it was adapted in the lab,” he said. “However, the alternative explanation, which most public health individuals go by, is that this virus was actually circulating in China, likely in Wuhan, for a month or more before they were clinically recognized at the end of December 2019.”
He added, “Dr. Redfield was mentioning he was giving an opinion as to a possibility, but again, there are other alternatives.”
White House COVID-19 Response Team news briefing, March 26, 2021.