Home / News / World /  Covid-19 vaccine study on preventing transmission is stalled

Plans have stalled for a large study on U.S. college campuses that was intended to answer a question critical to the coronavirus pandemic response: Do the new Covid-19 vaccines stop the virus from spreading, in addition to protecting individuals from getting sick?

A network of medical researchers who have helped run federally funded studies of Covid-19 vaccines were hoping to start a clinical trial of Moderna Inc.’s shot in more than 20,000 college students in January. The study would test whether the vaccine prevented transmission of the coronavirus from person to person and whether it prevented infections that don’t trigger symptoms.

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But last week, the researchers told about 20 universities that were considering participating in the study that it wouldn’t move forward yet, according to people involved in the effort. The researchers weren’t able to secure federal funding for the trial, which would have cost several hundred million dollars, and faced time constraints in getting the complex study up and running so it could yield results before students ended the spring semester, these people said.

“In the end, there just wasn’t enough support to get it off the ground at this point in time," said Myron Cohen, director of the Institute for Global Health and Infectious Diseases at the University of North Carolina. “We just could not get everything together to do it now."

The study had been planned by leaders of the Covid-19 Prevention Network, which the National Institute of Allergy and Infectious Diseases formed to conduct large studies of Covid-19 vaccines and treatments. The network includes clinical research sites around the U.S. that in the past have run studies of HIV/AIDS vaccines. Researchers from the network proposed the study to a public-private partnership led by the National Institutes of Health, known as Activ, which has crafted a research strategy.

The NIH and other federal agencies have funded the large efficacy trials of several Covid-19 vaccines, including Moderna’s, under the auspices of the Trump administration’s Operation Warp Speed initiative to develop and deliver Covid-19 vaccines.

A spokeswoman for the National Institute of Allergy and Infectious Diseases, which is part of the NIH, said NIAID was considering such a study but decided not to move forward with it because it had concerns about its feasibility, and it saw other paths to finding the same answers.

The spokeswoman said NIAID had concerns that university health-care workers were already overwhelmed with managing Covid-19 on campuses, and it would have been difficult to enlist them to also run a clinical trial. NIAID expects to learn more about the vaccines’ effect on transmission and asymptomatic infection from additional data from the existing efficacy trials and observational studies during the vaccine rollout.

The change of plans for the college-student study means that it might take longer to find out whether the new vaccines prevent transmission and asymptomatic infections, or that those questions will have to be answered in other ways.

U.S. regulators authorized the Moderna vaccine, and one from Pfizer Inc. and BioNTech SE, in December based on evidence that they protected people from Covid-19 with symptoms like cough and fever, including in severe cases. But these studies didn’t yield enough evidence of whether the shots prevent viral transmission and asymptomatic infections.

Public-health officials say the vaccines’ most important benefit to prevent severe disease in individuals. But if the shots also prevent asymptomatic cases and block transmission, they could hasten society’s return to normal life without mitigation measures like mask-wearing and physical-distancing.

The planned study would have used near-daily Covid-19 testing and contact tracing to determine whether vaccinated students subsequently contracted Covid-19—with or without symptoms—and whether they transmitted the virus to others. The study would have compared these rates with those seen in unvaccinated students, Dr. Cohen said.

Researchers believed colleges would have been ideal for the study because the virus has spread rapidly on some campuses where students live in close quarters. Many students’ infections are asymptomatic, and younger people generally are at lower risk of severe disease. Some colleges are already performing frequent Covid-19 testing and contact tracing among students.

In recent weeks, federal officials and government advisers publicly cited plans for the college campus study to address the question of a vaccine’s effect on transmission. “That is a critical thing to get answered: whether these vaccines can prevent asymptomatic transmission," Peter Marks, director of the division that evaluates vaccines at the Food and Drug Administration, told reporters shortly after the FDA authorized the emergency use of Moderna’s vaccine on Dec. 18.

One of the proponents of the study was Larry Corey, an infectious-disease specialist at the Fred Hutchinson Cancer Research Center in Seattle who helps lead the vaccine testing pipeline for the Covid-19 Prevention Network. Not knowing whether the shots prevent transmission means not knowing when it might be safe to have large gatherings or ease off wearing masks, he said.

“There’s a degree of scientific uncertainty here that’s going to last a very considerable period of time," he said.

Some of the colleges that were being considered for the study included Louisiana State University, the University of Michigan, the University of Washington, Morehouse College and the University of North Carolina, according to a person familiar with the matter.

Adam Lauring, an associate professor at Michigan’s medical school, was exploring the idea of enrolling students in the study. He said the Covid-19 Prevention Network told him last week that the study wouldn’t be moving forward for now.

Dr. Lauring said it is important to know if vaccinated people can still become infected and spread the virus. “Ultimately, controlling Covid is going to depend on shutting down transmission," he said.

Paul Offit, director of the vaccine education center at the Children’s Hospital of Philadelphia, said that until more is known about the effect on transmission, “I think we should be cautious when we get vaccinated. We should still wear masks and social distance because it’s a potentially fatal infection."

Moderna and Pfizer are planning to conduct their own evaluations of whether their vaccines prevent asymptomatic Covid-19 cases and viral transmission. Moderna said that in a preliminary analysis from its large study, there were fewer cases of asymptomatic infections among people after they received the first of two doses of its vaccine than among those who got a placebo. The company continues to study the matter. Pfizer said it is still evaluating its vaccine’s effect on transmission and asymptomatic disease.

This story has been published from a wire agency feed without modifications to the text.

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