SARS-CoV-2 Effects on Psychophysical Olfactory Scores: Prospective Study With Evaluation Before and 60-Days After Infection

The aim of this study was to prospectively evaluate the olfactory function in a series of individuals infected with SARS-CoV-2 and who had undergone psychophysical olfactory assessment prior to infection. Individuals unexposed to SARS-CoV-2 infection underwent a psychophysical evaluation of smell with the Sniffin' Sticks test. The subjects were followed prospectively and included in the study if they developed SARS-CoV-2 infection with a second test 60 days after recovery. At the 60-day follow-up of the 41 included subjects, 2 (4.9%) self-reported persistent olfactory dysfunction (OD). The differences between TDI scores before and after infection were statistically significant (37 [interquartile range (IQR), 34.25-39.25] vs 34.75 [IQR, 32.25-38]; p = .021). Analyzing the individual olfactory domains, the differences were significant for threshold (T) (9.75 [IQR, 9-11.25] vs 8.25 [IQR, 7.25-10.25]; p = .009) but not for odor discrimination (D) (p = .443) and identification (I) (p = .159). SARS-CoV-2 causes a significant reduction in the olfactory function, in particular affecting the olfactory threshold, even in subjects who do not self-report an OD.