Characteristics of the Anosmic Olfactory Mucosa

Inclusion Criteria: * Legally competent to vouch for their own study participation. * Informed and written consent for participation in this study. * Study group 1 (Post-COVID anosmia) 1. Diagnosed with persistent anosmia for approximately two years concurring with positive SARS-CoV-2 PCR-test between 2019 and 2020. 2. Sniffin'sticks test with a threshold-discrimination-identification-score(TDI)≤16 3. Between 25 and 35 years of age. Study group 2 (Post-trauma anosmia) 1. Diagnosed with persistent anosmia for approximately two years concurring with head trauma. 2. Sniffin'sticks test with a threshold-discrimination-identification-score(TDI)≤16 3. Between 25 and 35 years of age. Study group 3 (Controls): 1. Between 25 and 35 years of age. 2. Undergoing reposition of a nasal fracture in general anaesthesia Exclusion Criteria: * \<25 years of age. * \>35 years of age. * Chronic rhinosinusitis with/without polyps. * Nasal cancer. * Presence of viral or bacterial rhinosinusitis. * Uncontrolled allergic rhinosinusitis. * Coagulation deficiencies, e.g. haemophilia. * Use of anticoagulants. * Not able to undergo general anaesthesia. * Pregnancy. * Any use of nasal detumescence drugs ≤2 weeks before biopsy. * Any use of nasal steroids ≤3 months before biopsy. * Use of nasal inhaled recreational drugs ≤3 month before biopsy. * Participants not able to communicate in Danish or English. * Major Depression Inventory (MDI) score ≥27 \[49, 50\] * Mini Mental State Examination (MMSE) score ≤ 26 \[51\] * Study group 1 (Post-COVID anosmia) 1. Anosmia for less than two years or more than two and a half years. 2. No positive SARS-CoV-2 PCR-test concurring with olfactory dysfunction. 3. History of olfactory dysfunction before COVID-19 infection. * Study group 2 (Post-trauma anosmia) 1. Anosmia for less than two years or more than approximately two-three years. 2. Anosmia without concurring with head trauma 3. History of prior olfactory dysfunction before head trauma. * Study group 3 (Controls) 1. Known olfactory dysfunction.