1. Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
2. Department of Health Promotion, Faculty of Health, Medicine and Life Sciences, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, the Netherlands.
3. Department of Health Services Research, Faculty of Health, Medicine and Life Sciences, CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, the Netherlands.