[1] Univ Antwerp CDE, Vaccine & Infect Dis Inst, Ctr Evaluat Vaccinat, Unit Hlth Econ & Modelling Infect Dis, B-2610 Antwerp, Belgium
[2] Natl Alliance Christian Sickness Funds, B-1031 Brussels, Belgium
[3] Sci Inst Publ Hlth, B-1050 Brussels, Belgium
[4] Univ Leuven, Rega Inst Med Res, Dept Microbiol & Immunol, Lab Clin & Epidemiol Virol, B-3000 Leuven, Belgium
[5] Univ Sydney, Sch Publ Hlth, Sydney, NSW 2006, Australia