1. Division of Infectious Diseases and Hospital Epidemiology; University Hospital of Zurich, University of Zurich; Zurich Switzerland
2. Department of Infectious Diseases; Bern University Hospital and University of Bern; Bern Switzerland
3. University Hospital Geneva; Geneva Switzerland
4. University Hospital Lausanne; Lausanne Switzerland
5. University Hospital Basel; Basel Switzerland
6. Kantonsspital St. Gallen; St. Gallen Switzerland
7. University of Zurich; Institute of Medical Virology; Zurich Switzerland