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. 2021 Mar;11(3):e02006.
doi: 10.1002/brb3.2006. Epub 2021 Jan 19.

Olfactory function and viral recovery in COVID-19

Marco Mazzoli  1   2 , Maria Angela Molinari  1 , Manuela Tondelli  3 , Giada Giovannini  1   2 , Riccardo Ricceri  1 , Ludovico Ciolli  1   2 , Livio Picchetto  1 , Stefano Meletti  1   2
Affiliations

Olfactory function and viral recovery in COVID-19

Marco Mazzoli et al. Brain Behav. 2021 Mar.

Abstract

Background: Olfactory and taste disorders were reported in up to 30%-80% of COVID-19 patients. The purpose of our study was to objectively assess smell impairment in COVID-19 patients and to correlate olfactory function with viral recovery.

Methods: Between 15 and 30 April 2020, hospitalized patients with confirmed SARS-CoV-2 infection underwent an objective assessment of olfactory function with the Smell Identification subtest of the Sniffin' Sticks Test (SI-SST). Association between viral recovery and SI-SST performance was evaluated.

Results: 51 patients were enrolled (49% males, mean age 66.2 ± 14.6 years). At the time of test administration, 45% were clinically recovered and 39% were virus-free. Objective hyposmia/anosmia was found in 45% of the patients. Subjective olfactory disorders showed no association with the clinical or viral recovery status of the patients. On the contrary, none of the patients with anosmia and the 5% of hyposmic patients at test had viral recovery. The relative risk for hyposmic patients to be still positive at swab test was 10.323 (95% CI 1.483-71.869, p < .0001). Logistic regression analysis showed an independent and significant correlation between viral clearance and SI-SST scores (OR = 2.242; 95% CI 1.322-3.802, p < .003). ROC curve analysis confirmed that a SI-SST > 10.5 predicts viral clearance with 79% sensitivity and 87% specificity (AUC = 0.883).

Conclusion: Hyposmia is part of COVID-19 symptoms; however, only objectively assessed olfactory function is associated with viral recovery. SI-SST is an easy and safe instrument, and further large multicentric studies should assess its value to predict infection and recovery.

Keywords: COVID-19; SARS-CoV-2; anosmia; hyposmia; smell.

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Conflict of interest statement

M. Mazzoli, M.A. Molinari, M. Tondelli, G. Giovannini, R. Ricceri, L. Ciolli, and L. Picchetto report no disclosures. Stefano Meletti received research grant support from the Ministry of Health (MOH) and from the nonprofit organization foundation "Fondazione Cassa di Risparmio di Modena ‐ FCRM"; and has received personal compensation as scientific advisory board member for UCB and EISAI.

Figures

FIGURE 1
FIGURE 1
(a) Violin plots showing SI‐SST score distribution in patients with or without viral recovery (negative at 2 consecutive 24 hr apart nasopharyngeal swabs). The black line represents the mean score of each group. (b) Scatterplot showing SI‐SST score distribution as a function of time from symptom onset and viral recovery. (c) Receiver operating characteristic (ROC) curve for prediction of viral recovery based on SI‐SST score
See this image and copyright information in PMC

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