Anosmia/hyposmia differences between severe acute respiratory syndrome coronavirus 2 variants; objective olfactory function evaluation

Abstract

Objectives: This study aimed to investigate whether the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants cause more or less loss of smell than the wild type variant as a clinical finding that may guide physicians in addition to the increased mortality feature. Patients and Methods: In the prospective study, Connecticut Chemosensory Clinical Research Center (CCCRC) odor testing was performed on patients hospitalized for coronavirus disease 2019 (COVID-19) between May 2021 and December 2021, and variants of SARS-CoV-2 isolated from patients were analyzed. A total of 51 patients (30 males and 21 females; mean age 59.3±14.2 years; range, 29 to 88 years) were included in the study. Age, sex, and COVID-19 vaccine status of the patients were recorded. The patients were asked whether they had new-onset odor or taste complaints and whether they differently perceived smells they knew. Results: The delta variant was detected in 14 patients, the alpha variant was detected in 20 patients, and no variant of concern was detected in 17 patients. Odor disorders were present in 79.4% of all patients (13.73% anosmia, 15.69% severe hyposmia, 13.7% moderate hyposmia, and 37.2% mild hyposmia). There was no statistically significant difference between sex, age, smoking habits, presence of parosmia, degree of smell disorder, and Vicks definition results according to the variants (p>0.05). A statistically significant difference was found between alpha and delta variants in terms of patients' complaints of decreased smell and taste, mean olfactory threshold value, and mean olfactory score variables (p<0.05). There was no difference in terms of age and identification score. The complaints of smell and taste disorders, the mean threshold value of odor, and the mean odor score were found to be significantly lower in the delta variant than in the alpha variant. Conclusion: SARS-CoV-2 variants differ significantly in olfactory dysfunction. Future clinical and laboratory studies may show the diagnostic, clinical, and prognostic significance of olfactory nerve injury.