Interleukin-6 affects the severity of olfactory disorder: a cross-sectional survey of 148 patients who recovered from Omicron infection using the Sniffin’ Sticks test in Tianjin, China

Objectives: The mechanism of olfactory disorder (OD) in patients with COVID-19 is unclear. Our study aimed to elucidate the relationships between inflammatory factors and OD in a sample of patients infected with the Omicron variant, with a high vaccination rate in China. Methods: The Sniffin’ Sticks 12-item test was performed in a cross-sectional study of 148 recovered patients who were infected with the Omicron variant to evaluate OD severity. We compared demographic, laboratory, and clinical data. Results: A total of 148 patients infected with the Omicron variant were enrolled. A total of 129 cases of OD were detected. Increased inflammation contributed to OD severity, especially in the adult group. OD was shown to be aggravated by an increase in interleukin-6 levels. The adjusted odds ratio (OR) was 2.22 (95% confidence interval 0.98-5.05, P = 0.056) after adjustment for age, sex, and vaccine characteristics. Conclusion: These findings indicated that the prevalence of OD remains high in vaccinated patients infected with the Omicron variant and that the Sniffin’ Sticks 12-item test might be a feasible method to screen for OD. Interleukin-6 may play a role in the biochemical and pathological processes underlying OD.