Smell and Taste dysfunctions of COVID-19

Abstract

Olfactory and taste dysfunctions are characteristic of coronavirus disease 2019 (COVID-19), but their frequency and pathogenesis have changed with mutations in viral strains. Angiotensin-converting enzyme 2, a receptor for the spike protein of SARS-CoV2 in the olfactory epithelium, is involved in developing olfactory dysfunction. Most patients with olfactory dysfunctions recover in a few weeks. Still, there are cases in which the symptoms persist for several months or longer, and parosmia or phantosmia afflicts the patient. It is assumed that the damage extends to the olfactory nerve cells, resulting in sensorineural olfactory dysfunction similar to post-infectious olfactory dysfunction.