Josh Morrison isn’t a doctor or scientist, but as a well-intentioned activist he’s provoked a fierce debate over how to develop a coronavirus vaccine. To speed up testing, he wants to be deliberately infected with the coronavirus. And he’s drawn considerable attention to his cause by starting a nonprofit that already has recruited more than 37,000 volunteers to get infected too—all in the name of science.

What Morrison is advocating is known as a challenge trial. Participants are given a vaccine and then administered the virus to shorten the time it takes to determine a vaccine’s effectiveness. In traditional clinical field trials, scientists have to wait for vaccinated participants to encounter the virus naturally, which can take months.

Morrison’s quest has pushed