1. National Institute for Public Health and the Environment (RIVM) National Coordination Centre for Communicable Disease Control, Bilthoven, the Netherlands
2. Public Health Service The Hague, The Hague, the Netherlands
3. Medical Centre Haaglanden, The Hague, the Netherlands
4. Isala Klinieken Zwolle, Zwolle, the Netherlands
5. National Institute for Public Health and the Environment (RIVM) Centre for Infectious Disease Research, Diagnostics and Screening, Bilthoven, the Netherlands
6. Erasmus MC, Rotterdam, the Netherlands
7. Public Health Service Ijsselland, Zwolle, the Netherlands
8. National Institute for Public Health and the Environment (RIVM), Centre for Infectious Diseases, Epidemiology and Surveillance, Bilthoven, the Netherlands