WIRED UKThis story originally appeared on WIRED UK.Morrison, who is 34, felt powerless. He wanted to be able to do something constructive. It was in this context that he came across a paper in The Journal of Infectious Diseases which put forward the case for human challenge studies of Covid-19 vaccine candidates. Challenge studies purposely infect healthy volunteers with a pathogen in order to study a disease or test a treatment or vaccine. This paper suggested that using human challenge studies could speed up the development of a Covid-19 vaccine by months, potentially saving thousands of lives. “The idea of speeding that all up and getting this stuff done with is pretty appealing,” Morrison says. “And also, I thought that I personally could participate in one of these.”After contacting some friends, Morrison set up 1 Day Sooner, a group that advocates on behalf of volunteers for Covid-19 human challenge studies. No such studies are yet being conducted, but at the time of writing, more than 24,000 people from 102 countries have signed up on the 1 Day Sooner website to express an interest in taking part in one. Globally, there have now been more than five million reported cases of Covid-19, and 300,000 deaths. Should we let people volunteer to be purposely exposed to a virus we know can sometimes be fatal?
Challenge studies have been used in research on vaccines and treatments for diseases such as malaria, typhoid and influenza. But the idea of purposely exposing people to a disease—especially one that, like Covid-19, we do not yet have a specific treatment for—is ethically fraught. “It kind of goes against your natural inclination to intentionally infect someone with something,” says Charlier Weller, head of vaccines at the Wellcome Trust. In May, the World Health Organization (WHO) put together a list of criteria that would need to be met to make Covid-19 human challenge studies ethically acceptable, the first of which is scientific justification: what benefit could such a study offer?
A Dying Scientist's Rogue Vaccine Trial
The main argument for a human challenge study for a Covid-19 vaccine is speed. Normally, to test a vaccine, researchers would go through three phases of human trials. A phase one trial tests the vaccine in a small group of healthy volunteers to make sure it is safe. A phase two trial looks for signs that the vaccine is effective, for example by seeing if it produces the expected immune response. Finally, a phase three trial tests if it actually stops people from contracting the disease in the real world.
Haller believes in vaccines, which is why he volunteered to test three different influenza vaccines that weren’t yet approved by the Food and Drug Administration—including against H7N9, a strain of influenza seen as a plausible source of the next pandemic.“I know how much misery they prevent in the world,” says Haller, an associate professor of pediatrics at Saint Louis University School of Medicine.
The phase three trial takes the most time. It involves a larger group of volunteers, with some receiving the vaccine and the other receiving a placebo as a control. These volunteers then go about their normal lives, and researchers see how many people in each group wind up getting naturally infected.But letting nature take its course can be time-consuming. “[A phase three trial] can often take years, depending on the incidence of disease, and often involves thousands of people,” Weller says. In a challenge study, volunteers are given either the vaccine or placebo and are intentionally infected with the virus at a known moment in time, so there’s less waiting around to see the effects, and many fewer participants are needed. The volunteers would be kept in a specialized facility throughout the trial, to avoid transmitting the virus to third parties and make sure they have access to good medical care.