1. Health Protection Surveillance Centre, Dublin, Ireland
2. Vaccine European New Integrated Collaboration Effort (VENICE) Project
3. European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
4. Centers for Disease Control and Prevention, Atlanta, United States
5. Istituto Superiore di Sanitá, Rome, Italy
6. French Institute for Public Health Surveillance (Institut de Veille Sanitare, InVS), Saint-Maurice, France
7. CINECA Consortium of Universities, Bologna, Italy
8. Statens Serum Institut, Copenhagen, Denmark
9. National Institute of Public Health - National Institute of Hygiene, Warsaw, Poland
10. The gatekeepers are listed at the end of the article