Abstract
A significant reduction in smell and taste has been reported as one of the major symptoms following COVID-19 infection. This is so common that it has been proposed as the most relevant predictor for diagnosing infection. Different mechanisms by which viruses affect smell and taste have been proposed. ACE2 (angiotensin-converting enzyme 2) has been characterized as the main input receptor for the SARS-CoV-2 virus that interacts with its spikes, allowing it to enter the host cell through a fusion domain. It is mainly expressed in the upper respiratory tract, and the highest density of these proteins is found in the olfactory and gustatory epithelia. Currently, available data indicate that the most likely cause of anosmia during COVID-19 is an impaired function of olfactory sensory neurons, associated with infection and death of microvillar cells, and vascular pericytes. For taste, in the same way as for olfactory disorders, the pathogenesis of taste disorders in COVID-19 can cause indirect damage to the taste receptors through infection. Individuals with metabolic pathologies are susceptible to COVID-19 and are therefore, more vulnerable to disturbances in chemical senses and their consequences. In addition, recent studies show that COVID-19 may increase susceptibility to diabetes by directly acting on pancreatic β-cells.