Study group: Oliver Fuchs (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL); Department of Paediatric Respiratory Medicine, Inselspital, University Children's Hospital of Bern, University of Bern, Bern, Switzerland), Barbara Roesler (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Nils Welchering (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Naschla Kohistani-Greif (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Johanna Kurz (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL); Department of Paediatric Respiratory Medicine, Inselspital, University Children's Hospital of Bern, University of Bern, Bern, Switzerland), Katja Landgraf-Rauf (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Kristina Laubhahn (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Claudia Liebl (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Markus Ege (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Alexander Hose (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Esther Zeitlmann (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Mira Berbig (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Carola Marzi (Institut für Asthma- und Allergieprävention (IAP), Helmholtz Zentrum Munich, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Munich, Germany), Christina Schauberger (Department of Paediatric Allergology, Dr von Hauner Children's Hospital, Ludwig Maximilians University, Munich, Germany, and Comprehensive Pneumology Center, Munich (CPC-M), Germany; German Center for Lung Research (DZL)), Ulrich Zissler (Center of Allergy & Environment (ZAUM), Technical University of Munich and Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany; German Center for Lung Research (DZL), Munich, Germany), Carsten Schmidt-Weber (Center of Allergy & Environment (ZAUM), Technical University of Munich and Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany; German Center for Lung Research (DZL), Munich, Germany), Isabell Ricklefs (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Gesa Diekmann (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Lena Liboschik (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Gesche Voigt (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Laila Sultansei (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Gyde Nissen (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Inke R. König (Institute for Medical Biometry and Statistics, University Luebeck, University Medical Centre Schleswig-Holstein, Campus Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Anne-Marie Kirsten (Pulmonary Research Institute at LungenClinic Grosshansdorf, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Frauke Pedersen (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Henrik Watz (Pulmonary Research Institute at LungenClinic Grosshansdorf, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Benjamin Waschki (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Christian Herzmann (Research Center Borstel – Medical Clinic, Borstel, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Mustafa Abdo (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Heike Biller (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Karoline I. Gaede (Research Center Borstel – Medical Clinic, Borstel, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Xenia Bovermann (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Alena Steinmetz (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Berrit Liselotte Husstedt (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Catharina Nitsche (University Children's Hospital, Luebeck, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Vera Veith (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Marlen Szewczyk (LungenClinic Grosshansdorf GmbH, Grosshansdorf, Germany, and Airway Research Center North (ARCN), Germany; German Center for Lung Research (DZL)), Folke Brinkmann (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL); Department of Paediatric Pneumology, University Children's Hospital, Ruhr-University Bochum, Bochum, Germany), Aydin Malik (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Nicolaus Schwerk (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Christian Dopfer (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Mareike Price (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Adan Chari Jirmo (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Anika Habener (Department of Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), David S. DeLuca (Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Svenja Gaedcke (Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Bin Liu (Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Mifflin-Rae Calveron (Hannover Medical School, Hannover, Germany, and Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Germany; German Center for Lung Research (DZL)), Stefanie Weber (University Children's Hospital Marburg, University of Marburg, Germany, and University of Giessen Marburg Lung Center (UGMLC); Member of the German Center for Lung Research), Tom Schildberg (University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Pediatrics, Cologne, Germany), Silke van Koningsbruggen-Rietschel (University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Pediatrics, Cologne, Germany), Miguel Alcazar (University of Cologne, Faculty of Medicine and University Hospital Cologne, Translational Experimental Pediatrics – Experimental Pulmonology, Department of Pediatric and Adolescent Medicine, Germany; University of Cologne, Faculty of Medicine and University Hospital Cologne, Center for Molecular Medicine Cologne (CMMC), Germany; Excellence Cluster on Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Institute for Lung Health, University of Giessen and Marburg Lung Centre (UGMLC), Member of the German Centre for Lung Research (DZL), Gießen, Germany).

Conflict of interest: N. Maison, J. Omony, S. Illi, D. Thiele, A.M. Dittrich, C. Happle, M. Meyer, S. Foth and R. Grychtol have nothing to disclose. C. Skevaki reports grants and personal fees from Hycor Biomedical, Bencard Allergie, Thermo Fisher Scientific as well as grants from Mead Johnson Nutrition (MJN), Universities Giessen and Marburg Lung Centre, the German Centre for Lung Research (DZL), University Hospital Giessen and Marburg, Deutsche Forschungsgemeinschaft (DFG). T. Bahmer reports grants from the Federal Ministry for Education and Research (BMBF) for the German Center for Lung Research (DZL) and personal fees from AstraZeneca, GlaxoSmithKline, Novartis, Roche and Chiesi. M. Weckmann reports grants from Federal Ministry for Education and Research (BMBF), University of Luebeck and German Academic Exchange Service. B. Schaub reports grants from DFG, BMBF, the EU as well from GlaxoSmithKline, Sanofi and Novartis. H. Renz reports grants from German Center for Lung Disease (DZL) and Universities Giessen Marburg Lung Center. M.V. Kopp reports grants and personal fees from Allergopharma GmbH and Vertex GmbH; additional, personal fees from Sanofi GmbH, Infectopharm GmbH and Leti GmbH. E. Rietschel reports personal lecture payments for Nutricia Milupa GmbH and Novartis Pharma, and honoraria for participation in advisory boards for MICE-Mylan, Novartis Pharma GmbH and Boehringer Ingelheim GmbH. K.F. Rabe recieved personal payments or honoraria from AstraZeneca, Boehringer Ingelheim, Chiesi Pharmaceuticals, Novartis, Sanofi & Regeneron, GlaxoSmithKline, Berlin Chemie and Roche; K.F. Rabe also discloses participation on data safety monitoring boards/advisory boards for AstraZeneca and Sanofi Regeneron, and leadership or fiduciary role in the German Center for Lung Research (DZL), German Chest Society (DGP) and American Thoracic Society (ATS). G. Hansen reports grants from German Federal Ministry of Education and Research (BMBF) and German Research Foundation (DFG) as well as personal fees from Sanofi GmbH, MedUpdate, and Abbvie. E. von Mutius reports grants from the German Center for Lung Research (DZL) as well as royalties/licenses held by Elsevier GmbH, Gerog Thieme Verlag, Springer Verlag GmbH, Elsevier Ltd; furthermore, consultation fees were received from the Chinese University of Hong Kong, European Commission, HiPP GmbH and AstraZeneca; E. von Mutius also received payments and/or support for meetings/travel from the Massachusetts Medical Society, Springer-Verlag GmbH, Elsevier Ltd, Böhringer Ingelheim International GmbH, European Respiratory Society (ERS), University Utrecht, Salzburg, Colorado and Imperial College London, Springer Medizin Verlag GmbH, Japanese Society of Pediatric Allergy and Clinical Immunology, Klinkum Rechts der Isar, Paul-Martini-Stiftung; further support for meetings/travel was granted by Verein zur Förderung der Pneumologie am Krankenhaus Groshansdorf, Pneumologie Development Mondial Congress & Events GmbH, American Academy of Allergy, Asthma & Immunology, Margaux Orange, Volkswagen Stiftung, Österreichische Gesellschaft für Allergologie & Immunologie, OM Pharma SA, Hanson Wade Ltd, iKOMM GmbH, DSI Dansk Bornestma Center, American Thoracic Society, HiPP GmbH; E. von Mutius has patent EP2361632, EP1411977, EP1637147 and EP 1964570 (licensed to Protectimmun), furthermore patent LU101064 is pending; E. von Mutius participates in the following data monitoring or advisory boards: EXPANSE, BEAMS External Scientific Advisory Board, Journal of Allergy and Clinical Immunology: in Practice, Children's Respiratory and Environmental Workgroup (CREW), International Scientific & Societal Advisory Board of Utrecht Life Sciences, External Review Panel of the Faculty of Veterinary Science (University of Utrecht), Gottfried Wilhelm Leibniz Programme, Asthma UK for Applied Research, Advisory Board of The Lancet Respiratory Medicine, CHILD (Canadian Healthy Infant Longitudinal Development Study).