Thirty-five members of the US Congress have written to health authorities in the Trump Administration asking them to authorise accelerated trials to find a vaccine for the coronavirus. “Every week of delay in the deployment of a vaccine to the seven billion humans on Earth will cost thousands of lives,” they declare.
The route to a quick-fix vaccine passes through “challenge trials” – deliberately infecting human volunteers with the virus to see whether or not a vaccine works. A safe vaccine can take a decade to develop – the fastest have taken four years. But the devastation wreaked by the coronavirus has convinced a number of doctors, scientists and ethicists that it is worth taking the risk.
Challenge trials are not new. They have been used in the past to test medications – but for diseases which are well known, like influenza or cholera. A few hundred young and healthy volunteer participants would be given a placebo or the trial vaccine.
In a traditional clinical trial the participants would go about their daily lives until some of them were infected. In a challenge trial the volunteers, who are first given either the potential vaccine or a placebo, are deliberately infected. Researchers would be able to tell quickly whether the vaccine was safe and effective.
This approach could cut months, even years, off the time needed to make it available and for people to resume normal social life.
There are numerous problems with challenge trials. For one, it is risky. People in their 20s – from whom the participants would probably be drawn --- seldom become very sick with Covid-19. But there have been some deaths. Participants would have to appreciate the risks.
But as the American politicians write, “Our situation in this pandemic is analogous to war, in which there is a long tradition of volunteers risking their health and lives on dangerous missions for which they understand the risks and are willing to do so in order to help save the lives of others.”
The idea has sparked a heated debate amongst scientists and bioethicists. Arthur Caplan, a bioethicist at New York University, and Stanley Plotkin, a renowned vaccinologist who helped invent the rubella vaccine, endorsed the idea in an article in the journal Vaccine. (In this interview in Vice, Caplan makes a forceful, non-technical argument for challenge trials.) Plotkin claimed in an article in Science that a well-designed challenge trial could yield clear proof within two or three months.
A website set up to recruit volunteers for challenge trials, 1 Day Sooner, says that more than 9,000 people have signed up from 52 countries .
However, the US Food and Drug Administration is more cautious. “The FDA is exploring all possible options to most efficiently advance the development of safe and effective vaccines that will prevent COVID-19,” agency spokesman Michael Felberbaum told The Hill. “Human challenge studies used to develop a COVID-19 vaccine may present ethical and feasibility issues that can be avoided with the use of animal models.”
Myron Levine, an expert in challenge trials at Maryland School of Medicine, believes that conventional methods will yield results very quickly because of the level of infection in some locations. He is sceptical about challenge trials. “I cannot imagine that it would be ethical and would really speed up what we have to do,” he told Science.
Ethics, science, manufacturing, distribution: it’s important for researchers to cover all the bases, lest they end up with a catastrophe like thalidomide. Or like the situation which Will Smith’s character has to deal with in the zombie thriller I Am Legend. Watch Emma Thompson explain how her cancer cure works in this brilliant interview. And then it didn’t.
Michael Cook is editor of BioEdge
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