Support for Vaccine Challenge Trials Gains Momentum
Support for Vaccine Challenge Trials Gains Momentum

Support for Vaccine Challenge Trials Gains Momentum

The idea of deliberately infecting volunteers with SARS-CoV-2 has garnered significant attention as a potential avenue to speedier development, as the World Health Organization weighs in with recommendations.

Shawna Williams
Shawna Williams
May 11, 2020

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In the movie Contagion, a researcher from the Centers for Disease Control and Prevention goes rogue after seeing that a vaccine candidate has worked in a monkey. She injects herself with the formula and then goes to visit her father, who is hospitalized with the fictional virus MEV-1, to expose herself to the pathogen. She doesn’t fall ill, and the success of her risky act accelerates the rollout of a vaccine against the virus.

Contagion fans have noted a number of parallels between the movie’s fictional disease and COVID-19, and deliberate exposure to test a vaccine’s efficacy may be the next one. Some researchers are advocating for a more systematic version of the film’s approach, and the idea is gaining traction. The World Health Organization released guidelines last week on how such “challenge trials” might be conducted, and the US National Institutes of Health (NIH) is holding a meeting today (May 11) of a working group charged with drafting “a perspective on the scientific and practical considerations for a Covid-19 human challenge model,” the Financial Times reports.  

Ordinarily, “Safety of a vaccine must be confirmed by extensive animal work, followed by the inoculation of dozens of humans, then escalating to thousands,” write vaccine consultant Stanley Plotkin and New York University bioethicist Arthur Caplan in an upcoming article in the journal Vaccine. “That process normally takes months to years, during which SARS-2 will infect and possibly kill millions. Acceleration of that standard process is necessary.” They go on to propose human challenge trials as a way of achieving that acceleration.  

A similar argument was laid out in late March by a bioethicist and two epidemiologists in The Journal of Infectious Diseases, and last month by a bipartisan group of 35 US Representatives who urged the Food and Drug Administration (FDA) to consider approving such trials. 

The FDA would not comment when asked by NBC News if any plans for such trials have been submitted for approval, and no human challenge trials are yet underway in the US. NBC reports that the multinational testing company SGS and London-based hVIVO are planning such studies. More than 15,000 people worldwide have submitted their information to a website collecting names of potential volunteers for a human challenge trial. 

Some bioethicists tell NBC there isn’t yet enough information available to determine whether conducting such a trial would be ethical. And beyond ethical and legal issues, there are significant logistical challenges to conducting such an experiment. Vaccine researcher Peter Hotez of Baylor College of Medicine tells BuzzFeed that researchers would, for example, need to determine the minimum dose of virus that should be given and standardize the “challenge” virus and its delivery. Completing such steps will take time. 

“A challenge study captures the imagination,” bioethicist Seema Shah of Lurie Children’s Hospital of Chicago tells NBC. “But they have to work in a larger ecosystem of research, and we can’t pin all of our hopes on them.”