- Sigrid Gouma: a Centre for Infectious Disease Control , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands.
- Marion P G Koopmans: a Centre for Infectious Disease Control , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands.
- Rob S van Binnendijk: a Centre for Infectious Disease Control , National Institute for Public Health and the Environment (RIVM) , Bilthoven , The Netherlands.