1. University Medical Center Utrecht; Julius Center for Health Sciences and Primary Care; HP: Str. 6.131 PO Box 85500 Utrecht Netherlands 3508 GA
2. University Medical Center Utrecht; Department of Otorhinolaryngology & Julius Center for Health Sciences and Primary Care; PO Box 85500 Utrecht Netherlands 3508 GA
3. University Medical Center Groningen; Department of Epidemiology; Hanzeplein 1 PO Box 30.001 Groningen Netherlands 9700 RB
4. Faculty of Brain Sciences, University College London; evidENT, Ear Institute; 330 Grays Inn Road London UK WC1X 8DA
5. Wilhelmina Children's Hospital, University Medical Center Utrecht; Department of Pediatric Immunology and Infectious Diseases; PO Box 85090 Utrecht Netherlands 3508 AB