1. Division of Pediatric Pulmonology Children's Hospital of Eastern Switzerland St Gallen Switzerland
2. Institute of Social and Preventive Medicine University of Bern Bern Switzerland
3. Division of Respiratory and Critical Care University Children's Hospital Basel, University of Basel Basel Switzerland
4. Division of Respiratory Medicine, Department of Paediatrics, Inselspital, Bern University Hospital University of Bern Bern Switzerland