1 Dondena Centre for Research on Social Dynamics and Public Policy, Department of Social and Political Science, Bocconi University, Milan, Italy yuxi.wang@unibocconi.it.
2 Woking, UK.
3 National Education Union, London, UK.
4 The William Harvey Research Institute, Faculty of Medicine and Dentistry, Queen Mary University, London.
5 University of Leeds, Leeds, UK.
6 Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts, USA.
7 Dondena Centre for Research on Social Dynamics and Public Policy, Department of Social and Political Science, Bocconi University, Milan, Italy.
8 Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London.