1. Institute of Social and Preventive Medicine University of Bern Bern Switzerland
2. Paediatric Respiratory Medicine, Children's University Hospital of Bern University of Bern Bern Switzerland
3. Division of Respiratory Medicine, University Children's Hospital Zurich and Childhood Research Center University of Zurich Zurich Switzerland
4. University Children's Hospital Basel (UKBB) Basel Switzerland
5. PEDNET, Paediatric Clinical Trial Unit, Children's University Hospital of Bern University of Bern Bern Switzerland