Further, doctors are morally obliged to tell volunteers how to avoid getting infected. They cannot tell them to go maskless, or to seek out crowded spaces, even though from a narrowly scientific point of view this would improve their test results. It’s also impossible to monitor so many volunteers closely enough to determine if they are reporting their experiences inaccurately and skewing the results.

Rutgers University bioethicist Nir Eyal says that coronavirus challenge testing in the U.S could simultaneously “maximize utility and respect rights.” Researchers would use only “informed, willing, low-risk volunteers” from a population that is already in high-risk areas, he said.

Volunteers are abundant. An advocacy group called 1 Day Sooner has found 32,000 volunteers in 140 countries, mostly between the ages of 20 and 30, (old enough to consent but much less exposed to serious harm from Covid-19 than their elders) with no relevant underlying medical conditions. Strongly believing in effective altruism, Josh Morrison, who heads 1 Day Sooner, voluntarily donated one of his kidneys to a stranger, as did others helping with the campaign.

But Kantian objections are serious. Michael Rosenblatt, a Harvard Medical School professor and former chief medical officer of Merck Inc., objects that human challenge studies should only be contemplated when some lifesaving treatment, such as an antiviral medicine, is available for a candidate who gets sick. There is no such cure for Covid-19.

Then there is the problem of the unknown. Vaccines must pass muster with libertarians, descended from figures such as the enlightenment philosopher John Locke and the founding fathers of the U.S., who build morality around individual freedom. To counter libertarian objections, researchers must obtain “informed consent.”

Rosenblatt argues that when it comes to Covid-19, “It’s pretty hard to have informed consent when we barely know anything about this yet.” There are fears that the virus can cause lasting damage even in twentysomethings, for example, but little clear evidence. Can volunteers really consent to expose themselves to such poorly understood risks?

Finally, there is the appalling possibility of a volunteer dying. In 1999, this happened to Jesse Gelsinger, a healthy 18-year-old with a rare metabolic genetic disorder who volunteered for a conventional safety trial (not a challenge trial) of a virus-based gene therapy. His death was both a personal tragedy and a scientific disaster that “set the field of gene therapy back by at least two decades,” Rosenblatt said. “That hiatus deprived a generation of patients with genetic disorders of treatments.”

Morrison, of 1 Day Sooner, defends the right to volunteer for testing. Estimates at present are that the risk of death from Covid-19 for people in their 20s with no pre-existing conditions is under one in 10,000 — less than the risk of dying in childbirth while soldiers (whether volunteer or conscripted) face a far higher chance of dying on the battlefield.

How to Pay for It?
“A vaccine is meaningless if people are unable to afford it,” said John Young, the chief management officer of Pfizer Inc. Nobody asserts that drug companies should be able to charge whatever the market can bear for a Covid-19 vaccine.

But private companies like Pfizer have a responsibility to shareholders. Moreover, anyone who develops a successful coronavirus vaccine will have performed an immense service to humanity and will deserve to be rewarded. And so Pfizer defends its right to make a profit.