1. Section Pediatric Infectious Diseases, Laboratory of Medical Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
2. Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
3. Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven (RIVM), the Netherlands