Professor Christophe Fraser from the Nuffield Departments of Medicine and Population Health and Professor Michael Parker, Director of the Wellcome Centre for Ethics and Humanities and a member of the Steering Group of the Ethics in AI Institute, explain the epidemiology and ethics that have underpinned the development of the NHS mobile contact tracing app. Professor Fraser will summarise the science behind the epidemiological model city of 1 million inhabitants devised to inform the app’s configuration. Professor Parker will discuss the ethical considerations needed to foster well-founded public trust and confidence when deploying an app-based approach. Visit: www.coronavirus-fraser-group.org