Smell and Taste Disorders in COVID-19: A Literature Review
Naif Yaseen Albar*
Department of Otorhinolaryngology, Head and Neck Surgery, King Abdulaziz University College of Medicine, Rabigh, Saudi Arabia
*Corresponding Author: Naif Yaseen Albar, Department of Otorhinolaryngology, Head and Neck Surgery, King Abdulaziz University College of Medicine, Rabigh, Saudi Arabia,
May 25, 2022; Published: June 15, 2022
Background: There is increasing evidence that the sudden olfactory dysfunctions (OD) and gustatory dysfunctions (GD) especially in the absence of nasal obstruction, rhinorrhea, or any upper respiratory symptoms, are common early symptoms of COVID-19. The objective of this review was to identify regional and worldwide prevalence of OD and GD in patients with COVID-19.
Methods: A search of the literature using keyword combinations was performed on the 1st of July 2020 among 4 major databases: PubMed, ScienceDirect, Web of Science, and Scopus. Preprints databases (Medrxiv, Biorxiv) were also searched for unpublished manuscripts. Only primary studies that reported on prevalence of OD/GD and written in English were selected. Data synthesis was narrative. Following the review, websites of relevant professional bodies were searched for guidelines and recommendations. Risk of bias was assessed with a 10-item tool.
Results: Twenty-nine articles reported OG or GD symptoms in 15830 patients. Studies have demonstrated great heterogeneity in the reported prevalence of anosmia as a COVID-19 symptom, from 5.1% to 98%. Caucasians have a higher prevalence than East Asians.
Discussion: Preliminary evidence suggests that differences in host or virus genotypes dominating different geographical regions may explain such heterogeneity in the reported prevalence of OD/GD among COVID-19 patients. However, there was no standardized method of detecting anosmia, limiting any strong conclusions. In regions with higher prevalence, OD/GD can be useful as a sensitive biomarker of COVID-19 that may help prioritization of COVID-19 testing and promote self-isolation which would reduce exposure to contagious but otherwise asymptomatic individuals who are much more difficult to identify.
Keywords: COVID-19; Taste Disorders; Olfaction Disorders; Prevalence; Anosmia
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