Competing Interests: Conflict of interest: C. Porsbjerg declares grants or contracts, consulting fees and payment or honoraria from AstraZeneca, GlaxoSmithKline, Novartis, TEVA, Sanofi, Chiesi and ALK in the 36 months prior to manuscript submission. Conflict of interest: A.H. Maitland-van der Zee declares unrestricted research grants from Vertex and Boehringer Ingelheim, and is the principal investigator of a Precision Medicine for more Oxygen (P4O2) public private partnership sponsored by Health Holland involving cash or in kind contributions from Boehringer Ingelheim, Breathomix, Fluidda, Ortec Logiqcare, Philips, Quantib-U, Smartfish, SODAQ, Thirona, TopMD and Novartis; consulting fees paid to their institution by AstraZeneca and Boehringer Ingelheim; and payment or honoraria paid to their institution by GlaxoSmithKline, all in the 36 months prior to manuscript submission. They declare that they are an unpaid member of the Data Safety Monitoring Board of the SOS BPD Study; that they are unpaid president of the Federation of Innovative Drug Research in the Netherlands (FIGON); and that they are president of the European Association of Systems Medicine. Conflict of interest: G. Brusselle declares payment or honoraria from AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, Novartis, Sanofi and Teva in the 36 months prior to manuscript submission. Conflict of interest: G.W. Canonica declares no competing interests. Conflict of interest: A. Agusti declares no competing interests. Conflict of interest: R. Faner declares research grant payments from GlaxoSmithKline, Menarini, AstraZeneca, ISC-III and the Spanish National Health Service; consulting fees from GlaxoSmithKline; and payments or honoraria from Chiesi, all in the 36 months prior to manuscript submission. Conflict of interest: C.F. Vogelmeier declares grant payments to their institution from the German Ministry of Education and Science (BMBF), AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Grifols and Novartis; consulting fees from AstraZeneca, Boehringer Ingelheim, CSL Behring, Chiesi, GlaxoSmithKline, Menarini, Novartis and Nuvaira; payments or honoraria from Aerogen, AstraZeneca, Boehringer Ingelheim, CSL Behring, Chiesi, GlaxoSmithKline, Menarini and Novartis, all in the 36 months prior to manuscript submission. Conflict of interest: M. Nawijn declares unrestricted research grant payments to their institution from Chan Zuckerberg Initiative and GlaxoSmithKline in the 36 months prior to manuscript submission; and that they are coordinator of the Human Cell Atlas Lung Biological Network. Conflict of interest: M. van den Berge declares research grant payments to their institution from GlaxoSmithKline, AstraZeneca, Novartis, Genentech and Roche in the 36 months prior to manuscript submission. Conflict of interest: F. Rusconi declares no competing interests. Conflict of interest: C. Pilette declares no competing interests. Conflict of interest: V. Ramiconi declares unrestricted educational grant payments to her organisation from Novartis, Pfizer, AstraZeneca, Chiesi, GlaxoSmithKline, AbbVie, LeoPharma, Boehringer Ingelheim, Sanofi, Regeneron, OM Pharma, Merck Sharp & Dohme, Roche and DBV Technologies, in the 36 months prior to manuscript submission. Conflict of interest: C. Coleman is an employee of the European Lung Foundation. Conflict of interest: R. Chaudhuri declares funding from 3TR European Union Innovative Medicines Initiative 2 to their institution for the present manuscript. They also declare grant funding from AstraZeneca within a Medical Research Council project; lecture fees from GlaxoSmithKline, AstraZeneca, Teva, Chiesi, Sanofi and Novartis; support for attending conferences from Chiesi, Napp, Sanofi, Boehringer Ingelheim, GlaxoSmithKline and AstraZeneca; and participation on advisory boards for GlaxoSmithKline, AstraZeneca, Teva, Chiesi and Novartis, all in the 36 months prior to manuscript submission. Conflict of interest: K.F. Chung declares grant payments to their institution from the Medical Research Council (precision medicine for severe asthma), the Engineering and Physical Sciences Research Council (air pollution and asthma) and GlaxoSmithKline (eosinophils); consulting fees from the scientific committee of the Clean Breathing Institute (funded by the GlaxoSmithKline consumer division); speaking fees for engagements from Novartis and AstraZeneca; an educational grant paid to their institution for the 11th London International Cough Symposium from AstraZeneca, Merck, Shionogi, Nocion, Bellus and Bayer; participation on a data safety management board for Nocion (antitussive); and participation on advisory boards for Nocion, Shionogi and Merck (antitussives) and GlaxoSmithKline, Roche and Novartis (asthma and COPD), all in the 36 months prior to manuscript submission. Conflict of interest: J. Wedzicha declares grant payments to their institution from GlaxoSmithKline, AstraZeneca, Novartis, Genentech, Boehringer Ingelheim and Chiesi; paid participation on a Data Safety Monitoring Board for Virtus; and editorship of the American Journal of Respiratory and Critical Care Medicine, for which an honorarium is paid jointly to them and their institution. Conflict of interest: S. Saglani declares no competing interests. Conflict of interest: M.P. Van der Schee declares consulting fees from Owlstone Medical in the 36 months prior to manuscript submission; and that they hold stock or stock options in Owlstone Medical and Sanome. Conflict of interest: L. Heaney declares grant payments to their institution from Novartis UK, GlaxoSmithKline, Amgen, Genentech/Hoffmann la Roche, AstraZeneca, Medimmune, Aerocrine and Vitalograph; payments or honoraria from Novartis, Genentech/Hoffmann la Roche, Sanofi, Evelo Biosciences, GlaxoSmithKline, AstraZeneca, Teva, Theravance and Circassia; support for attending meetings from AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline and Napp; and participation on advisory boards for Novartis, Genentech/Hoffmann la Roche, Sanofi, Evelo Biosciences, GlaxoSmithKline, AstraZeneca, Teva, Theravance and Circassia, all in the 36 months prior to manuscript submission. Conflict of interest: A. Bourdin declares unrestricted grant payments from AstraZeneca and Boehringer Ingelheim; advisory board fees from AstraZeneca, GlaxoSmithKline, Regeneron, Sanofi, Novartis, Chiesi, Amgen; lecture payments from AstraZeneca, GlaxoSmithKline, Regeneron, Sanofi, Novartis, Chiesi and Amgen; and support for attending meetings from AstraZeneca, GlaxoSmithKline, Regeneron, Sanofi and Novartis, all in the 36 months prior to manuscript submission. Conflict of interest: G. Roberts declares funding from 3TR European Union Innovative Medicines Initiative 2 to their institution for the present manuscript. Conflict of interest: R. Djukanovic declares consulting fees from Synairgen plc in the 36 months prior to manuscript submission; that they are chair of the European Respiratory Society Clinical Research Collaboration on severe asthma (SHARP); and that they hold shares in Synairgen plc. Conflict of interest: P. Kuna declares lecture fees from Adamed, AstraZeneca, Boehringer Ingelheim, Berlin Chimie, Menarini, Chiesi, HAL Allergy, Lekam, Mylan, Novartis, Polpharma and Teva in the 36 months prior to manuscript submission. Conflict of interest: M. Kupczyk declares funding from 3TR European Union Innovative Medicines Initiative 2 for the present manuscript. They also declare payment or honoraria from AstraZeneca, Chiesi, GlaxoSmithKline, Novartis, Lekam, Alvogen, Emma, Nexter and Berlin Chemie in the 36 months prior to manuscript submission. Conflict of interest: J. Axmann declares no competing interests. Conflict of interest: H. Staudinger declares that they are an employee of Sanofi Genzyme; and that they hold stock or stock options in Sanofi and Merck. Conflict of interest: G.W. Clarke declares that they are an employee of AstraZeneca; and that they hold stock or stock options in AstraZeneca. Conflict of interest: S.E. Dahlen declares consulting fees from AstraZeneca, Caiman Chemicals, GlaxoSmithKline, Merck, Novartis, Regeneron, Sanofi and Teva, outside the present manuscript. Conflict of interest: C. Brightling declares support from 3TR European Union Innovative Medicines Initiative 2 for the present manuscript. They also declare grant payments to their institution from GlaxoSmithKline, AstraZeneca, Novartis, Chiesi, Sanofi, Genentech, Merck, Mologic, 4DPharma and Gossamer; consulting fees paid to their institution from GlaxoSmithKline, AstraZeneca, Boehringer Ingelheim, Novartis, Chiesi, Sanofi, Genentech, Merck, Mologic, 4DPharma, Gossamer, TEVA, Regeneron, Roche and CSL Behring, all in the 36 months prior to manuscript submission.