1. Global Health Policy Unit, School of Social and Political Science, University of Edinburgh, Edinburgh, UK.
2. Department of Health Services Research and Policy, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK.
3. Department of Public Health, Environments and Society, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK.
4. UK PRP SPECTRUM Consortium, London School of Hygiene and Tropical Medicine, London, UK.