1. Division of Pediatric Respiratory Medicine; Hospital Universitario Donostia-Instituto Biodonostia; San Sebastián Spain
2. Biomedical Research Centre Network for Respiratory Diseases (CIBERES); San Sebastián Spain
3. Department of Pediatrics; University of the Basque Country (UPV/EHU); San Sebastián Spain
4. Pediatric Pulmonary Unit; Department of Pediatrics, Obstetrics, Gynecology and Preventive Medicine; Hospital Universitario Vall d'Hebron; Universitat Autònoma de Barcelona; Barcelona Spain
5. Division of Infectious Diseases; Department of Pediatrics; Nationwide Children's Hospital; The Ohio State University; Columbus OH USA
6. Pediatric Pulmonary Section; Hospital Torrecárdenas; Almería Spain
7. Pediatric Pulmonary Unit; Hospital Clínico Universitario; Universidad de Valencia; Valencia Spain
8. Department of Pediatrics; Hospital San Juan de la Cruz; Úbeda Spain
9. Pediatric Pulmonary Unit; Hospital Universitario Nuestra Señora de la Candelaria; Tenerife Spain
10. Pediatric Pulmonary Section; Hospital Universitario Virgen Macarena; Universidad de Sevilla; Sevilla Spain
11. Pediatric Pulmonary Section; Hospital Universitario La Fe; Valencia Spain
12. Pediatric Pulmonary Section; Hospital Clínico Universitario Virgen de la Arrixaca; Universidad de Murcia; Murcia Spain
13. Pediatric Pulmonary Unit; Hospital Materno-Infantil; Málaga Spain
14. Pediatric Pulmonary Unit; Hospital Clínico Universitario; Tenerife Spain
15. Pediatric Pulmonary and Allergy Unit; Hospital Reina Sofía; Córdoba Spain
16. Pediatric Pulmonary Section; Hospital Universitario Son Espases; Palma de Mallorca Spain
17. Pediatric Pulmonary Section; Hospital Universitario La Paz; Madrid Spain
18. Pediatric Pulmonary and Allergy Unit; Hospital Universitario 12 de Octubre; Madrid Spain