Olfactory Dysfunction: A Highly Prevalent Symptom of COVID-19 With Public Health Significance

Abstract

Objective: Coronavirus disease 2019 (COVID-19) is a global pandemic affecting millions of individuals, killing hundreds of thousands. Although typically described with characteristic symptoms of fever, cough, and shortness of breath, greater understanding of COVID-19 has revealed myriad clinical manifestations. Olfactory dysfunction (OD)-hyposmia and anosmia-has recently been recognized as an important symptom of COVID-19 and increasingly gained traction as a public health tool for identifying COVID-19 patients, in particular otherwise asymptomatic carriers who, unawares, may be major drivers of disease spread. The objective of this study is to review the scientific evidence about anosmia in COVID-19.

Data sources: PubMed, Google Scholar, and Web of Science.

Review methods: Comprehensive literature search of primary studies pertinent to the objectives of this review using the chosen data sources.

Conclusions: Current evidence shows that OD is highly prevalent in COVID-19, with up to 80% of patients reporting subjective OD and objective olfactory testing potentially showing even higher prevalence. OD is frequently accompanied by taste dysfunction. Up to 25% of COVID-19 patients may experience sudden-onset OD as the first symptom. A large proportion of COVID-19 OD cases may resolve over the period of a few weeks.

Implications for practice: Sudden anosmia should be considered a symptom of COVID-19. Assessing for sudden-onset anosmia may increase sensitivity of COVID-19 screening strategies, in particular for identifying patients at the earliest stages of disease. Since many cases of OD due to COVID-19 may resolve in the short term, conservative management, including observation, is reasonable, while advanced imaging is unnecessary.

Keywords: COVID-19; SARS-CoV-2; anosmia; coronavirus; hyposmia; olfaction; olfactory dysfunction; olfactory function; smell.