1. a Regional Center for Disease Control of South Eastern France, ORS PACA , Marseille
2. b INSERM, Institut Paoli Calmettes , Research Unit 379 'Epidemiology and Social Sciences applied to medical innovation', Marseille
3. c Department of Economics , University of Aix-Marseille II , France
4. d Department of Public Health and Policy , London School of Hygiene and Tropical Medicine , London , UK