Self-reported anosmia and dysgeusia as key symptoms of coronavirus disease 2019

To slow down the transmission of coronavirus disease 2019 (COVID-19), it is important to identify specific symptoms for effective screening. While anosmia/hyposmia and dysgeusia/ageusia have been identified as highly prevalent symptoms, there are wide geographic variations, necessitating the regional evaluation of the prevalence of the symptoms.

A cross-sectional study was performed to evaluate the self-reported symptoms among adults (over 18 years old) who underwent COVID-19 tests at an ambulatory assessment centre. We identified 1,345 patients (102 positive and 1,243 negative) who visited the assessment centre between March 16 and April 15, 2020. We randomly sampled negative patients in a 1:3 ratio. The primary outcome was the prevalence of self-reported anosmia/hyposmia and dysgeusia/ageusia. Logistic regression was performed to evaluate the association between COVID-19 positivity and loss of smell and taste.

Fifty-six of 102 (50%) positive patients and 72 of 306 (23.5%) negative patients completed the survey. Anosmia/hyposmia and dysgeusia/ageusia were more prevalent among COVID-19 positive patients (41.1% v. 4.2%, p < 0.001 for smell and 46.4% v. 5.6%, p < 0.001 for taste). Anosmia/hyposmia and dysgeusia/ageusia were independently highly associated with COVID-19 positivity (adjusted odds ratios 14.4 and 11.4 for smell and taste, respectively).

In this Canadian study, smell and taste loss may be key symptoms of COVID-19. This evidence can be helpful in the clinical diagnosis of COVID-19, particularly settings of limited testing capacity.