1. Epidemiology Department, EpiConcept, Paris, France
2. These authors contributed equally to this manuscript
3. Department for Infectious Disease Epidemiology Respiratory Infections Unit, Robert Koch Institute, Berlin, Germany
4. Istituto Superiore di Sanità, Rome, Italy
5. National Centre of Epidemiology, Institute of Health Carlos III, Madrid, Spain
6. Department of Public Health, Strategic Planning and Epidemiology, Office of the Chief Medical Officer, Budapest, Hungary
7. Health Service Executive-Health Protection Surveillance Centre, Dublin, Ireland
8. University of Medicine and Pharmacy ‘Carol Davila’, ‘Institutul National de Cercetare-Dezvoltare pentru Microbiologie si Immunologie ´Cantacuzino´, Bucharest, Romania
9. Department of Epidemiology, National Institute of Health Dr. Ricardo Jorge, Lisbon, Portugal
10. Polish National Institute of Public Health, Warsaw, Poland
11. National Centre of Epidemiology/ CIBER Epidemiología y Salud Pública (CIBERESP), Institute of Health Carlos III, Madrid, Spain