1. Department of Infectious Diseases, Inselspital, Bern University Hospital, University of Bern , Bern , Switzerland
2. Service of Infectious Diseases, Lausanne University Hospital and University of Lausanne , Lausanne , Switzerland
3. Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich , Zurich , Switzerland
4. Institute of Medical Virology, University of Zurich , Zurich , Switzerland
5. Department of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, University of Basel , Basel , Switzerland
6. Division of Infectious Diseases, Regional Hospital of Lugano , Lugano , Switzerland
7. Division of Infectious Diseases, Cantonal Hospital of St. Gallen , St. Gallen , Switzerland
8. Division of Infectious Diseases, Geneva University Hospital, University of Geneva , Geneva , Switzerland
9. Institute for Infectious Diseases, University of Bern , Switzerland
10. Institute of Social and Preventive Medicine, University of Bern , Bern , Switzerland