1. Department of Microbiology & Immunology Allergy and Clinical Immunology Research Unit KU Leuven Leuven Belgium
2. Department of Otorhinolaryngology, Head-Neck Surgery University of Crete School of Medicine Heraklion Greece
3. Department of Social Medicine Faculty of Medicine University of Crete Heraklion Greece
4. 1st Department of Otorhinolaryngology, Head and Neck Surgery AHEPA HospitalAristotle University of Thessaloniki Thessaloniki Greece
5. Clinical Department of Otorhinolaryngology, Head and Neck Surgery University Hospitals Leuven Leuven Belgium
6. Department of Otorhinolaryngology Academic Medical Center Amsterdam The Netherlands