Alterations in smell or taste in individuals infected with SARS-CoV-2 during periods of Omicron variant dominance

Abstract

Objectives: To characterize the prevalence, severity, correlation with initial symptoms, and role of vaccination in patients with COVID-19 with smell or taste alterations (STAs).

Methods: We conducted an observational study of patients infected with SARS-CoV-2 Omicron admitted to three hospitals between May 17 and June 16, 2022. The olfactory and gustatory functions were evaluated using the taste and smell survey and the numerical visual analog scale at two time points.

Results: The T1 and T2 time point assessments were completed by 688 and 385 participants, respectively. The prevalence of STAs at two time points was 41.3% vs 42.6%. Furthermore, no difference existed in the severity distribution of taste and smell survey, smell, or taste visual analog scale scores between the groups. Patients with initial symptoms of headache (P = 0.03) and muscle pain (P = 0.04) were more likely to develop STAs, whereas higher education; three-dose vaccination; no symptoms yet; or initial symptoms of cough, throat discomfort, and fever demonstrated protective effects, and the results were statistically significant.

Conclusion: The prevalence of STAs did not decrease significantly during the Omicron dominance, but the severity was reduced, and vaccination demonstrated a protective effect. In addition, the findings suggest that the presence of STAs is likely to be an important indicator of viral invasion of the nervous system.

Keywords: Anosmia; COVID-19; Dysgeusia; Olfactory and gustatory dysfunction; SARS-CoV-2.

Figure 1

Prevalence and severity grading in different conditions. (a) Among the 613 vaccinated patients, the prevalence of smell or taste alterations decreased with increasing number of vaccination doses. (b) Prevalence in different time windows from the onset of infection: within 3 days (49.4%, 95% CI 37.8-61.0%), within 7 days (47.9%, 95% CI 40.5-55.3%), and within 14 days (40.0%, 95% CI 36.0-44.1%). (c) No difference in the severity distribution of TSS, smell, or taste VAS scores was observed between the two timepoints, and most patients showed mild changes. TSS, Taste and Smell Survey; VAS, visual analog scale.

Figure 2

Education, initial symptoms, vaccination in patients with altered taste and smell. (a) Risk factors for altered smell or taste. (b) Prevalence of participants with different initial symptoms; and those who had headache (51.4% vs 39.5%, P = 0.03) and muscle pain (85.7% vs 40.8%, P = 0.04) as initial symptoms showed significantly higher prevalence.