1. Department of Infectious Disease Control, Municipal Public Health Service Rotterdam-Rijnmond, Rotterdam, The Netherlands
2. Department Research and Business Intelligence, Municipality of Rotterdam, Rotterdam, The Netherlands
3. Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
4. Epidemiology and Surveillance Unit, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands