Infectious disease “challenge” studies, in which healthy participants are deliberately infected with pathogens to investigate the cause, prevention, and treatment of infectious diseases, hold great potential for delivering high-quality data about new interventions. Infectious challenge studies may be used to address a variety of scientific questions, such as demonstrating a causative role for a specific infectious agent in a particular disease, testing the ability of a drug to prevent or ameliorate disease, or testing the efficacy of a prophylactic vaccine.