1 Paediatric Pulmonology and Allergy, Children's Doctor Service, University of Heidelberg, Heidelberg, Germany. Electronic address: Prof.Fritzsching@kinderarzt-hd.de.
2 Respiratory Section, Department of Translational Medicine, University of Ferrara, Ferrara, Italy.
3 Department of Respiratory Medicine, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.
4 ALK-Abelló, Hørsholm, Denmark.
5 Institute of Clinical Trials and Methodology UCL, London, United Kingdom.