A Harvard University Wyss Institute-led collaboration spanning four research labs and hundreds of miles has used the institute’s organ-on-a-chip (Organ Chip) technology to identify the antimalarial drug amodiaquine as a potent inhibitor of infection with SARS-CoV-2, the virus that causes COVID-19. The Organ Chip-based drug testing ecosystem established by the collaboration greatly streamlines the process of evaluating the safety and efficacy of existing drugs for new medical applications, and provides a proof-of-concept for the use of Organ Chips to rapidly repurpose existing drugs for new medical applications, including future pandemics. The research is reported in Nature Biomedical Engineering.