Emily Y Y Chan1, Katharine Wright2, Michael Parker3. 1. JC School of Public Health and Primary Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. Electronic address: emily.chan@cuhk.edu.hk. 2. Nuffield Council on Bioethics, London, UK. 3. Wellcome Centre for Ethics and Humanities, Nuffield Department of Population Health, University of Oxford, Oxford, UK.