1. Population Health Sciences University of Bristol Bristol UK
2. National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Behavioural Science and Evaluation Bristol UK
3. Division of Infectious Diseases and Global Public Health University of California San Diego CA USA
4. Department of Sexual Health, Cardiff Vale University Health Board Cardiff UK
5. National Institute for Health and Care Excellence London UK
6. Sigma Research, Faculty of Public Health & Policy London School of Hygiene and Tropical Medicine London UK