1. University of Zurich, Epidemiology, Biostatistics and Prevention Institute (EBPI), Zürich, Switzerland
2. General Practitioner, Amersfoort, The Netherlands
3. Valladolid National Influenza Center, Microbiology and Immunology Department, Hospital Clinicon, Valladolid, Spain
4. Department of Infectious Diseases Epidemiology, National Institute of Public Health, Prague, Czech Republic
5. Department of Epidemiology and Biostatistics, Third Faculty of Medicine, Charles University, Prague, Czech Republic
6. Department of Social Medicine and Public Health, Medical University of Warsaw, Warsaw, Poland
7. Department of Paediatrics with Clinical Assessment Unit, Medical University of Warsaw, Warsaw, Poland
8. Department of Pediatrics, Children's Clinic Hospital, Faculty of Medicine, Transilvania University Brasov, Brasov, Romania
9. Hellenic Center for Disease Control and Prevention, Athens, Greece
10. Department of Pediatrics, Riga Stradins University, Riga, Latvia
11. Faculty of Public Health, Slovak Medical University, Bratislava, Slovak Republic
12. Royal College of General Practitioners, Wokingham, Berkshire, UK