1. Interuniversity Institute for Biostatistics and Statistical Bioinformatics; Hasselt University; Agoralaan 1 Building D 3590 Diepenbeek Belgium
2. Centre for Health Economics Research and Modelling Infectious Diseases and Centre for the Evaluation of Vaccination; Vaccine & Infectious Disease Institute; University of Antwerp; Universiteitsplein 1 2610 Antwerp Belgium