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      Predictive Value of Sudden Olfactory Loss in the Diagnosis of COVID-19

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          Recent reports suggest that sudden smell loss might be a symptom of SARS-CoV-2 infection. The aim of this study was to investigate the frequency of olfactory loss in an outpatient population who presented to a coronavirus testing center during a 2-week period and to evaluate the diagnostic value of the symptom “sudden smell loss” for screening procedures.


          In this cross-sectional controlled cohort study, 500 patients who presented with symptoms of a common cold to a corona testing center and fulfilled corona testing criteria completed a standardized diagnostic questionnaire which included the patients' main symptoms, time course, and an additional self-assessment of the patients' current smell, taste function, and nasal breathing compared to the level before the onset of symptoms.


          Out of the 500 patients, 69 presented with olfactory loss. Twenty-two of them subsequently tested positive for SARS-CoV-2. Only 12 out of the patients without olfactory loss tested positive, resulting in a frequency of 64.7% for the symptom “sudden smell loss” in COVID-19 patients. Compared to COVID-19 patients without smell loss, they were significantly younger and less severely affected. Changes in nasal airflow were significantly more pronounced in SARS-CoV-2 negative patients with olfactory complaints compared to the patients with smell loss who tested positive for SARS-CoV-2. By excluding patients with a blocked nose, the symptom “sudden smell loss” can be attested a high specificity (97%) and a sensitivity of 65% with a positive predictive value of 63% and negative predictive value of 97% for COVID-19.


          Considering the high frequency of smell loss in non-hospitalized COVID-19 patients, acute olfactory impairment should be recognized as an early symptom of the disease and should be tested for on a regular basis. In contrast to other acute viral smell impairment, COVID-19-associated smell loss seems to be only rarely accompanied by a severely blocked nose.

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          Most cited references 4

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          Non-neural expression of SARS-CoV-2 entry genes in the olfactory epithelium suggests mechanisms underlying anosmia in COVID-19 patients

          Recent reports suggest an association between COVID-19 and altered olfactory function. Here we analyze bulk and single cell RNA-Seq datasets to identify cell types in the olfactory epithelium that express molecules that mediate infection by SARS-CoV-2 (CoV-2), the causal agent in COVID-19. We find in both mouse and human datasets that olfactory sensory neurons do not express two key genes involved in CoV-2 entry, ACE2 and TMPRSS2. In contrast, olfactory epithelial support cells and stem cells express both of these genes, as do cells in the nasal respiratory epithelium. Taken together, these findings suggest possible mechanisms through which CoV-2 infection could lead to anosmia or other forms of olfactory dysfunction.
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            Interpreting a covid-19 test result

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              Non-neural expression of SARS-CoV-2 entry genes in the olfactory epithelium suggests mechanisms underlying anosmia in COVID-19 patients


                Author and article information

                ORL J Otorhinolaryngol Relat Spec
                ORL J. Otorhinolaryngol. Relat. Spec
                ORL; journal for oto-rhino-laryngology and its related specialties
                S. Karger AG (Allschwilerstrasse 10, P.O. Box · Postfach · Case postale, CH–4009, Basel, Switzerland · Schweiz · Suisse, Phone: +41 61 306 11 11, Fax: +41 61 306 12 34, )
                11 June 2020
                : 1-6
                aSmell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
                bDivision of Infectious Diseases, TU Dresden, Dresden, Germany
                Author notes
                *Antje Haehner, Smell and Taste Clinic, Department of Otorhinolaryngology, TU Dresden, DE–01307 Dresden (Germany), antje.haehner@
                Copyright © 2020 by S. Karger AG, Basel

                This article is made available via the PMC Open Access Subset for unrestricted re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the COVID-19 pandemic or until permissions are revoked in writing. Upon expiration of these permissions, PMC is granted a perpetual license to make this article available via PMC and Europe PMC, consistent with existing copyright protections.

                Page count
                Figures: 1, Tables: 1, References: 15, Pages: 6
                Smell and Taste Corner


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