Challenge trials — in which human volunteers are deliberately infected with pathogens that can get them sick — have a long history, according to a recent New York Times opinion piece. The article describes a British research center where volunteers were deliberately infected with coronaviruses in a quest to find a cure for the common cold. However, challenge trials are less common in the United States, due in part to differences in regulatory and ethical considerations between the two nations. Click the link to learn more about what the possible benefits of challenge trials can be, and about the ethical arguments against them.