1. Department of Public & Global Health , Division of Infectious Diseases, Epidemiology, Biostatistics and Prevention Institute, , Zurich , Switzerland
2. University of Zurich , Division of Infectious Diseases, Epidemiology, Biostatistics and Prevention Institute, , Zurich , Switzerland
3. Division of Hygiene and Infectious Diseases, Institute of Hygiene and Environment , Hamburg , Germany
4. Swiss Tropical and Public Health Institute , Basel , Switzerland
5. University of Basel , Basel , Switzerland
6. Department of Epidemiology , Epidemiology, Biostatistics and Prevention Institute, , Zurich , Switzerland
7. University of Zurich , Epidemiology, Biostatistics and Prevention Institute, , Zurich , Switzerland