Nir Eyal1, Marc Lipsitch2, Peter G Smith3. 1. Center for Population-Level Bioethics, and Departments of Health Behavior, Society & Policy (SPH) and Philosophy (SAS), Rutgers University, New Brunswick, New Jersey, USA. 2. Center for Communicable Disease Dynamics, Department of Epidemiology, and Departments of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA. 3. Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom.