When will we get a vaccine? That’s the question Americans have been asking since the novel coronavirus shut down much of the country in March. Dr. Anthony Fauci says it could happen this year. Others think it will take a lot longer. The HPV vaccine took fifteen years to develop. The chickenpox vaccine took twenty-eight. No widely effective vaccine has ever been developed for many life-threatening viruses, including cytomegalovirus and HIV.
One potential way to speed up the development of a vaccine for Covid-19 is a “challenge study,” in which researchers give healthy subjects a prospective vaccine and then infect them with the coronavirus. In conventional trials researchers typically give subjects either a test vaccine or a placebo and follow them over time in their ordinary living conditions to see if the vaccine is effective. But there’s no need to wait for a naturally occurring infection in a challenge study, which allows it to be shorter and to require far fewer subjects. Yet such a study would also require deliberately giving those subjects a potentially deadly illness for which there is no good treatment, and for some observers, that’s a deal-breaker. A joint statement by the AIDS Vaccine Advocacy Coalition and the Treatment Action Group says, “Until there is an approved treatment, a challenge trial with a potentially fatal and as-yet untreatable pathogen is unacceptable.”
Nonetheless, the drumbeat for Covid-19 challenge studies is growing louder, and some of the most energetic drummers are bioethicists. Nir Eyal, a bioethicist at Rutgers, was one of the first to call for them.1 His proposal, cowritten with the epidemiologists Marc Lipsitch of Harvard and Peter Smith of the London School of Hygiene and Tropical Medicine, appeared online in late March. Challenge studies have also been endorsed by the NYU bioethicist Arthur Caplan and the vaccinologist Stanley Plotkin.2 Julian Savulescu and Dominic Wilkinson, bioethicist-physicians at Oxford, have raised the moral stakes even higher by proposing not just that researchers conduct Covid-19 challenge studies but that the first human subjects could be elderly nursing home patients. “Their motives might be purely altruistic,” Savulescu and Wilkinson wrote. “Or they may be fatalistic or wish to die, or at any rate not care if they die sooner rather than later.”3
The utilitarian argument for challenge studies is straightforward: calculate the number of lives risked and compare it to the potential number of lives saved. Backers of challenge studies point to a study (based on data from China) that estimates the risk of death from Covid-19 for a healthy adult between the ages of twenty and twenty-nine at 0.03 percent.
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