1. GSK, Wavre, Belgium
2. Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
3. University of Pennsylvania School of Medicine, Doylestown, PA, USA
4. Vaxconsult, Doylestown, PA, USA
5. Centre for the Evaluation of Vaccination, Vaccine & Infectious Diseases Institute, University of Antwerp, Antwerp, Belgium