1. Institute of Social and Preventive Medicine University of Bern Bern Switzerland
2. Division of Pediatric Cardiology, Pediatric Heart Center University Children's Hospital Zurich Zurich Switzerland
3. Children's Research Center University Children's Hospital Zurich Switzerland
4. Division of Paediatric Respiratory Medicine and Allergology, Department of Paediatrics, Inselspital, Bern University Hospital University of Bern Bern Switzerland
5. Department of Paediatrics, PEDNET, Paediatric Clinical Trial Unit, Inselspital, Bern University Hospital University of Bern Bern Switzerland