1. Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich
2. Swiss National Center for Retroviruses, Institute of Medical Virology
3. Laboratory of Virology, Division of Infectious Diseases, Geneva University Hospital
4. Department of Biomedicine-Petersplatz, University of Basel
5. Division of Immunology and Allergy
6. Department of Infectious Diseases, Berne University Hospital and University of Berne
7. Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel
8. Division of Infectious Diseases, University Hospital Lausanne
9. Division of Infectious Diseases, Regional Hospital Lugano
10. Division of Infectious Diseases, Cantonal Hospital St. Gallen, Switzerland
11. Institute of Social and Preventive Medicine, University of Zurich