1. Centre for Infectious Diseases, Epidemiology and Surveillance, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
2. Department of Medical Microbiology and Immunology, Diakonessenhuis, Utrecht, The Netherlands
3. Centre for Infectious Diseases Research, Diagnostics and Screening, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands