Alterations in Smell or Taste in Individuals Infected with SARS-CoV-2 During Periods of Omicron Variant Dominance: A Cross-Sectional Observational Study

Background: Anosmia and dysgeusia are key symptoms of SARS-CoV-2 infection. We aimed to characterize the prevalence, severity, timing, associated symptoms, and impact of vaccination in COVID-19 patients exhibiting these symptoms.Methods: We conducted an observational study of patients with mild SARS-CoV-2 Omicron variant infections admitted to three mobile hospitals between April 20 and May 16, 2022. Olfactory and gustatory function were evaluated using the Taste and Smell Survey (TSS) and the numerical visual analog scale (VAS). Primary outcomes included the prevalence, severity, correlation with initial symptoms, the impact of personal factors and vaccination.Findings: The T1 and T2 timepoint assessments were completed by 688 and 385 participants, respectively. The prevalence of anosmia or dysgeusia in group T1 was 41%, which was non-significantly different from group T2. Furthermore, no difference existed in the severity distribution of TSS, smell, or taste VAS scores between the groups. In group T1, 613 patients had received inactivated SARS-CoV-2 vaccine; the prevalence of anosmia or dysgeusia after receiving different doses was: one: 66·7%, two: 46·4%, and three: 37·5%. Individuals with higher education; three-dose vaccination; no symptoms yet; or initial symptoms of cough, throat discomfort, and fever were significantly less prevalent. Moreover, the two groups showed significant differences in education level (p = 0·001) and distribution of initial symptoms (p = 0·0005). Prevalence was significantly higher in patients with initial symptoms of headache (p = 0·02874) and muscle pain (p = 0·04398).Interpretation: The prevalence of anosmia or dysgeusia in SARS-CoV-2-infected patients did not decrease significantly during infection with the Omicron variant, but severity was reduced, and vaccination demonstrated a protective effect. Additionally, the findings suggest that the presence of smell or taste alterations is likely to be an important indicator of viral invasion of the nervous system, and an urgent need exists to explore early intervention to reduce prevalence and protect neurological function.Funding Information: The National Natural Science Foundation of China (grant number:8227122); Natural Science Foundation of Shanghai (grant number:20ZR1442900); Shanghai Fourth People's Hospital, School of Medicine, Tongji University (grant numbers: sykyqd01901, SY-XKZT-2021-2001).Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: The study was approved by the Medical Ethics Committee of Shanghai Fourth People's Hospital affiliated with Tongji University (2022061-001). Electronic informed consent was obtained from all participants.