Kruthika Thangavelu1, Kyriakos Martakis2,3, Silke Fabian4, Mahima Venkateswaran5, Bernhard Roth3, Dirk Beutner6, Ruth Lang-Roth4. 1. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Marburg, University of Gießen and Marburg, Marburg, Germany. 2. Department of International Health, CAPHRI - Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands. 3. Department of Pediatrics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany. 4. Department of Otorhinolaryngology, Head and Neck Surgery, University of Cologne, Cologne, Germany. 5. Global Health Cluster, Division for Health Services, Norwegian Institute of Public Health, Oslo, Norway. 6. Department of Otorhinolaryngology, Head and Neck Surgery, University of Göttingen, Göttingen, Germany.