University of Basel - Basel Institute for Clinical Epidemiology and Biostatistics, University of Basel - Surgical Outcome Research Center Basel, Sanitas Insurance Zurich, Helsana Insurance Zurich, CSS Insurance, Lucerne, University of Basel - Department of Clinical Research, University of Basel - Division of Infectious Diseases and Hospital Hygiene, University of Basel - Centre for Primary Health Care, St. George’s University of London - Paediatric Infectious Diseases Research Group and University of Basel - Basel Institute for Clinical Epidemiology and Biostatistics