Weighing the risk and benefit of human challenge trials

Weighing the risk and benefit of human challenge trials

A range of voices, from medical experts to politicians, are increasingly calling for a controversial voluntary program to test vaccines on people deliberately infected with COVID-19.

In the U.S., more than 16,000 willing participants have joined an advocacy group, and 35 members of Congress have asked regulators to consider the use of human challenge trials to help find a vaccine for the COVID-19. In Europe, London’s hVIVO and the Swiss-based SGS are working to launch similar studies, and the WHO itself has already published a working document outlining criteria for an ethically acceptable design.

A “human challenge trial” is a controversial way to test coronavirus vaccines that would deliberately infect people with a virus that has killed some 285,000 people worldwide and has no cure.

A vaccine is the only real way people can go back to their daily lives without fear of contracting the virus—back to sports stadiums, birthday parties, family visits, and most importantly, work, with an estimated 33 million jobs lost in the U.S. alone. Until one is found, social distancing could be an almost permanent state of reality and fears will continue of a second major outbreak of the virus this winter.

The problem is that vaccines take time to test and develop. The final phase of testing often requires tracking up to tens of thousands of people to see who actually becomes infected, sometimes over several years.

As a result, leading epidemiologists and vaccionologists are arguing in favor of human challenge studies as a way of speeding up the process. They claim that if designed correctly and carried out with consent, such trails could save an untold number of lives.

There are currently no public plans for such a study in the U.S., but both experts and politicians are pushing for one—and volunteers are quickly coming forward. An advocacy group known as 1DaySooner has already signed up 16,213 from 106 different countries.

Political support is also growing. In April, 35 members of Congress signed a letter written by their colleagues Bill Foster and Donna Shalala to the Commissioner of the Food and Drug Administration and Secretary of Health and Human Services, urging them to speed up the approval and deployment of a vaccine, including the use of the aforementioned trials.

“We wanted to let the regulators know that we in Congress understand the justifiable risks involved in human challenge trials,” Foster said in an interview with The FT. “(But) they may be essential if we want to sort through realistic vaccine candidates to find the one that works best — or as an insurance if something goes wrong and the first vaccines don’t work as well as we hope, or if the virus mutates and we have to identify rapidly the best alternatives.”

Notable voices within the pharmaceutical industry have also been supportive. Paul Stoffels, chief scientist at Johnson & Johnson, said his company would consider using a human challenge trial for its COVID-19 vaccine to quicken the process, as long as such a study was deemed legally and ethically acceptable.

The fallout to the COVID-19 crisis will involve analyzing many such ethical questions, not only to protect those especially vulnerable to infection or mortality, but also those who have no option but to return to jobs and professions that put them directly in the firing line of the virus. And of course, there will be no easy answers.


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Paul Imison
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