1. Department of Infectious Diseases; Bern University Hospital; University of Bern; Bern Switzerland
2. Division of Infectious Diseases and Hospital Epidemiology; University Hospital Zurich; University of Zurich; Zurich Switzerland
3. Institute of Medical Virology; University of Zurich; Zurich Switzerland
4. Division of Infectious Diseases and Hospital Epidemiology; University Hospital Basel; University of Basel; Basel Switzerland
5. Division of Infectious Diseases; University Hospital Lausanne; Lausanne Switzerland
6. Division of Infectious Diseases and Hospital Epidemiology; Cantonal Hospital St Gallen; St Gallen Switzerland
7. Institute for Infectious Diseases; University of Bern; Bern Switzerland
8. Division of Infectious Diseases; Regional Hospital Lugano; Lugano Switzerland