1. Paediatric Department, University Hospitals Würzburg, Würzburg, Germany;
2. Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland;
3. Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland;
4. Institute of Sports Medicine, Hannover Medical School, Hannover, Germany;
5. Service de Pneumologie et Allergologie Pédiatriques, AP-HP Hôpital Necker Enfants Malades, Université Paris Descartes, Paris, France;
6. Department of Paediatric Respiratory and Sleep Medicine, Royal Hospital for Sick Children, Edinburgh, United Kingdom;
7. Department of Pediatrics, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania;
8. Montreal Children’s Hospital, McGill University Health Centre, Montreal, Quebec, Canada; and
9. Division of Paediatric Pulmonology and Allergology, Department of Paediatrics and Adolescent Medicine, Medical University of Graz, Graz, Austria