Study of the Pathogenesis of Olfactory Disorders in COVID-19

Olfactory and taste dysfunctions are common and early onset in COVID-19, especially in pauci symptomatic patients, and may be the main clinical manifestations of the infection. Olfactory dysfunction could result from infection of the olfactory system by SARS-CoV-2 or from inflammation induced by the virus. While the recent development of COVID-19 pulmonary lesion research has revealed a viral, inflammatory and vascular origin, factors that cause olfactory disorders in COVID-19 are just beginning. Acute anosmia observed in some patients with COVID-19 could result from: * the direct infection of olfactory sensory neurons or neural stem cells of the olfactory mucosa, * an underlying inflammation of the olfactory mucosa, leading to possible neurodegeneration of olfactory sensory neurons, and neural stem cells of the olfactory mucosa, by analogy with the respiratory viruses responsible for chronic rhinosinusitis. It is therefore necessary to conduct a virological, cellular, immunological and inflammatory study of the olfactory epithelium from COVID-19 patients with isolated anosmia to identify the origin of these olfactory disorders. This study is a case-control study to characterize the molecular and cellular anomalies of the olfactory epithelium of COVID-19 patients with isolated anosmia, by comparison with the olfactory epithelium of non-infected subjects. Following measures will be performed at inclusion : * Taste and olfactory function evaluation by a self-questionnaire taste and smell survey (TTS) and a visual analogue scale (VAS) * Nasal swab sampling for collection of epithelium cells and olfactory mucus.