Trials take time: The first phase typically takes months, and the second two take years.
As a result, some experts have called for replacing conventional Phase III testing with human-challenge trials. In The Journal of Infectious Diseases last month, the bioethicist Nir Eyal and the epidemiologists Marc Lipsitch and Peter Smith argued that the idea, while risky, could shave months off the process. “Every week that vaccine rollout is delayed will be accompanied by many thousands of deaths globally,” they wrote. “If the use of human challenge helped to make the vaccine available before the epidemic has completely passed, the savings in human lives could be in the thousands or conceivably millions.”
How would it work?
In the authors’ proposed design, the study would rely entirely on young, healthy volunteers who fully understand the risks of participating. (To the authors, “young” might mean 20 to 45; to others, 18 to 30 or even 18 to 25.) Conventional Phase III trials typically require thousands of volunteers, but a human-challenge trial might need only 100. All participants would remain isolated in comfortable state-of-the-art facilities, with access to “excellent” health care.
Who in the world would volunteer to get infected?
Actually, a lot of people, according to Josh Morrison and Sophie Rose, the co-founders of an organization called 1DaySooner, which has gathered signatures from over 8,000 potential volunteers. In The Washington Post, Mr. Morrison and Ms. Rose argue that the idea is not as radical as it sounds: According to one study, the coronavirus’s fatality rate for 20- to 29-year-olds in China was 3 in 10,000 — the same as that of kidney donation surgery and roughly twice that of childbirth in the United States.
“We and many others are willing to take on what we see as an acceptable individual risk to serve the public and the people we care about,” they write. “As willing and well-informed volunteers, whose autonomy ought to be respected, we feel challenge trials are justified if they mean a vaccine arrives even one day sooner.”
Would it be ethical?
We already allow people to risk their lives for the collective good, Dr. Lipsitch, Dr. Eyal and Dr. Smith say. Firefighters, for example, are routinely called upon to rush into burning buildings. (And today, of course, delivery drivers and grocery clerks are being asked to accept a level of risk they did not sign up for.) The question, then, is whether the study’s potential cost would be low enough to warrant its potential benefit. Besides recruiting only healthy, young volunteers and guaranteeing them the best care, the authors delineate four ways in which the study would minimize net risk:
-The vaccine may protect some of those who receive it.
-Absent an effective vaccine, a high proportion of the general population is likely to get Covid-19, so some volunteers may simply be pushing their illnesses forward.
-Only people who already have an especially high risk of exposure would be recruited (e.g., New Yorkers).
-Volunteers would get priority for any treatments that may become available.
