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

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.