1. Department of Otolaryngology, Örebro University Hospital, Örebro, Sweden;
2. Faculty of Medicine and Health, School of Medical Science, Örebro University, Örebro, Sweden;
3. Department of Microbiology and Immunology, Institution of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden;
4. Department of Medical Education, Faculty of Medicine and Health, Örebro University, Örebro, Sweden