1. Regional Coordinating Centre for Nosocomial Infection Control (CClin Paris – Nord), Paris, France
2. Home Health Care of the Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
3. French Institute for Public Health Surveillance (Institut de Veille Sanitaire, InVS), Saint Maurice, France
4. Department of epidemiology and biostatistics, EHESP French School of Public Health, Rennes, France
5. The members of this group are listed at the end of the article