Ewen Calloway in Nature:
As hundreds of millions of people, maybe billions, avoid social contact to spare themselves and their communities from coronavirus, researchers are discussing a dramatic approach to research that could help end the pandemic: infecting a handful of healthy volunteers with the virus to rapidly test a vaccine. Many scientists see a vaccine as the only solution to the pandemic. Clinical safety trials began this month for one candidate vaccine, and others will soon follow. But one of the biggest hurdles will be showing that a vaccine works. Typically, this is done through large phase III studies, in which thousands to tens of thousands of people receive either a vaccine or a placebo, and researchers track who becomes infected in the course of their daily lives. A quicker option would be to conduct a ‘human challenge’ study, argue scientists in a provocative preprint published this week1 . This would involve exposing perhaps 100 healthy young people to the virus and seeing whether those who get the vaccine escape infection. Nir Eyal, the director of the Center for Population-Level Bioethics at Rutgers University in New Brunswick, New Jersey, and lead author of the preprint, tells Nature how the study could be done safely and ethically. Participants, he argues, might even be better off for it.
How could you conduct such a study?
You would start only after some preliminary testing to ensure that a vaccine candidate is safe and that it accomplishes an immune response in humans. You then gather a group of people at low risk from any exposure — young and relatively healthy individuals — and ensure that they are not already infected. You give them either the vaccine candidate or a placebo and wait for enough time for an immune response. And then you expose them to the virus.