Coronavirus disease 2019 (COVID-19)-related smell and taste impairment with widespread diffusion of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) Omicron variant

Background: The aim of this study was to estimate the prevalence of self-reported chemosensory dysfunction in a study cohort of subjects who developed a mild-to-moderate coronavirus disease 2019 (COVID-19) in the period from January 17, 2022, to February 4, 2022 (Omicron proxy period) and compared that with a historical series of patients testing positive for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection between March and April, 2020 (comparator period).

Methods: Prospective study based on the 22-item Sino-Nasal Outcome Tool (SNOT-22), item "sense of smell or taste" and additional outcomes.

Results: Patients' characteristics and clinical presentations of COVID-19 were evaluated and compared in 779 patients, 338 of the study cohort and 441 of the historical series. The prevalence of self-reported chemosensory dysfunction during the proxy Omicron period (32.5%; 95% confidence interval [CI], 27.6-37.8) was significantly lower from that during the comparator period (66.9%; 95% CI, 62.3-71.3) (p < 0.001). Nearly one-quarter of patients (24.6%; 95% CI, 20.1-29.5) reported an altered sense of smell during the proxy Omicron period compared to 62.6% (95% CI, 57.9-67.1) during the comparator period (p < 0.001). Similarly, the prevalence of an altered sense of taste dropped to 26.9% (95% CI, 22.3-32.0) during the proxy Omicron period from 57.4% (95% CI, 52.6-62.0) during the comparator period (p < 0.001). The severity of chemosensory dysfunction was lower in the proxy Omicron period compared to the comparator period (p < 0.001).

Conclusion: The prevalence and the severity of COVID-19-associated smell and taste dysfunction has dropped significantly with the advent of the Omicron variant but it still remains above 30%.