University of Geneva - Infection Control Programme, University of Geneva - Infection Control Programme, Imperial College London - MRC Centre for Global Infectious Disease Analysis, Geneva University Hospitals - Laboratory of Virology, Geneva University Hospitals - Laboratory of Virology, Geneva University Hospitals and Faculty of Medicine - Division of Prison Health, Imperial College London - MRC Centre for Global Infectious Disease Analysis, University of Geneva - Infection Control Programme, Geneva University Hospitals - Occupational Health Service, University of Geneva - Infection Control Programme, University of Geneva - Infection Control Programme, University of Geneva Hospitals and Faculty of Medicine - Infection Control Programme, Geneva University Hospitals - Clinique de Joli-Mont, Geneva University Hospitals - Department of Rehabilitation and Geriatrics, Imperial College London - Health Protection Research Unit in Healthcare Associated infections and Antimicrobial Resistance and University of Geneva - Faculty of Medicine