In a letter to the FDA last week, 35 federal lawmakers recommend the agency consider approving human “challenge” trials for COVID-19, which would infect healthy volunteers with the deadly virus to test efficacy of a vaccine. But the FDA and some researchers have expressed concern over the ethics involved.

Comparing the current crisis to a state of war, the letter says, “The enormous human cost of the COVID-19 epidemic alters the optimization of the risk/benefit analysis in favor of more rapid approval and deployment.”

“Congress understands that a more risk-tolerant development process is likely appropriate in the case of a COVID-19 vaccine, and justifiable risks may be taken,” says the letter, cosponsored by Reps. Bill Foster (D-Ill.) and Donna Shalala (D-Fla.), a former HHS Secretary.

An FDA spokesman expressed skepticism about deliberately infecting and endangering healthy individuals, an idea that flies in the face of most federal regulations on protection of human research subjects. Instead, animal testing could be used, the spokesman said.

David Forster, chief compliance officer of WCG Clinical and its IRB division, agrees. “IRBs would be very reluctant,” Forster says, “to approve a trial without some kind of mitigation (such as using a weakened strain or a population unlikely to have severe reactions) to protect the safety of subjects.

But several prominent scientists have weighed in on Congress’ side, including vaccinologist Stanley Plotkin, (codeveloper of the rubella vaccine) of the University of Pennsylvania, and New York University bioethicist Arthur Caplan. Writing in the journal Vaccine, the two question whether deployment of a vaccine should wait for results of controlled clinical trials or “whether to expedite vaccination by moving quickly through animal studies and doing human challenge studies in volunteers.”

“In the case of SARS-2 infection, a challenge study could take advantage of the lower rate of death in18- to 29-year-olds,” they say. “In that age group in China, the death rate was 0.03 percent, not negligible but relatively uncommon.”

Some young people are willing to step up to the challenge. More than 2,000 people from 52 countries have volunteered through a website called “1 Day Sooner” that is dedicated to gathering a pool of prequalified healthy volunteers to have at the ready should a human challenge trial be initiated.

Regardless of how many people are ready to volunteer, the ethical question remains. Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics, says he doubts IRBs would approve any trial with this level of risk to participants.