U.K. Challenge Study Will Expose Healthy Volunteers To The Coronavirus : Shots - Health News Exposing people to a potentially fatal disease could hasten understanding of COVID-19 and development of new vaccines and treatments. But the risks of such studies raise serious ethical questions.

Why Scientists Are Infecting Healthy Volunteers With The Coronavirus

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MARY LOUISE KELLY, HOST:

A controversial experiment has just begun in England. Researchers are deliberately exposing volunteers to the coronavirus that causes COVID-19. The goal is to speed up the development of new vaccines and treatments. But as NPR science correspondent Joe Palca reports, some question whether the benefits of these so-called human challenge experiments are worth the risks.

JOE PALCA, BYLINE: Human challenge experiments differ from other studies of COVID-19 in one crucial way.

CHRISTOPHER CHIU: The main difference is the control.

PALCA: Christopher Chiu is an infectious disease researcher at Imperial College London. He says with a challenge study, you know exactly when a person was exposed to the virus and exactly how much virus they were exposed to. Without knowing those things, you have to wait until people are exposed to the virus by chance.

CHIU: You'll end up having to reproduce a lot more people, give a lot more people your candidate vaccine before you can even hope to see the results.

PALCA: Indeed, it took many months and tens of thousands of volunteers to show the current crop of vaccines work. A challenge study could in theory have made that much easier and faster, but it does mean exposing perfectly healthy people to a potentially fatal disease. Chris Chiu says he and his colleagues are acutely aware of that. That's why they only plan to include certain kinds of people in their studies.

CHIU: We know from over a year of the pandemic now that young, healthy adults are at very low risk of getting severe COVID.

PALCA: Chiu says in addition to using only healthy young adults, the experiments will be carried out in a hospital with ample experience caring for COVID-19 patients. But studying only young adults is one of the flaws people see in challenge studies to test the efficacy of a vaccine, for example.

SEEMA SHAH: The data you get from a challenge study about whether that works is not really going to give you the kind of information you want.

PALCA: Seema Shah is a lawyer and medical ethicist at Northwestern University Feinberg School of Medicine. Shah says it's important to know if a vaccine works in older people, unhealthy people or people with different ethnic backgrounds. You don't get that from a challenge study.

SHAH: When this all started early in the pandemic, there was one big reason for doing these challenge studies, and that was to accelerate vaccine testing.

PALCA: But now multiple COVID-19 vaccines have been shown to work. Still, such studies may be useful for testing vaccines in the future. For example, if coronavirus cases become less common, it will take far more than 30 or 40,000 volunteers to tell if a new vaccine is significantly better than the ones presently available. And challenge studies should make comparing vaccines head-to-head much easier.

KANTA SUBBARAO: So in those circumstances, a human challenge infection model could be very helpful.

PALCA: Kanta Subbarao is a virologist and director of the World Health Organization's influenza research lab in Melbourne, Australia. But she's concerned that not enough is known about the risks of being exposed to SARS-coronavirus-2, the virus that causes COVID-19, even for healthy young adults.

SUBBARAO: Now, we talked early on about whether we should even consider SARS-coronavirus-2 and said we would not. But we are exploring the possibility of some of the common cold coronaviruses.

PALCA: She thinks doing that might provide clues to a universal coronavirus vaccine, one that would prevent both COVID-19 and the common cold. Right now Christopher Chiu and his colleagues are trying to determine the minimum amount of virus it takes to make someone sick with COVID-19. After that, they can turn their attention to testing new treatments and vaccines.

Joe Palca, NPR News.

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