Project description:BackgroundCOVID-19 threatens the global community because a large fraction of infected people are asymptomatic, yet can effectively transmit SARS-CoV-2. Finding and isolating these silent carriers is a crucial step in confining the spread of the disease. A sudden loss of the sense of smell has been self-reported by COVID-19 patients across different countries, consistent with expression of the molecular factors mediating SARS-CoV-2 uptake into human olfactory epithelial supporting cells. However, precise quantification of olfactory loss in asymptomatic COVID-19 carriers is missing to date.MethodsTo quantify olfactory functions in asymptomatic COVID-19 patients, we designed an olfactory-action meter that determines detectability indices at different odor concentrations and an olfactory matching accuracy score using monomolecular odors. The optimization of test parameters allowed us to reliably and accurately assess olfactory deficits in a patient within 20 minutes.FindingsMeasurement of detection indices at low concentrations revealed a 50% reduction in asymptomatic COVID-19 carriers. Further, patients with better detection scores showed significantly reduced olfactory matching accuracies compared to normal healthy subjects. Our quantification of olfactory loss, considering all parameters, identified 82% of the asymptomatic SARS-CoV-2 carriers with olfactory deficits. However, on subjective evaluation, only 15% of the patients noticed a compromised ability to smell.InterpretationCompromised olfactory fitness can serve as a strong basis for identifying asymptomatic COVID-19 patients. Detailed design specifications and protocols provided here should enable the development of a sensitive, fast, and economical screening strategy that can be administered to large populations to prevent the rapid spread of COVID-19.FundingThis work was supported by the DBT - Wellcome Trust India Alliance intermediate grant (IA/I/14/1/501,306 to N.A.) and UGC NET Fellowship (A.B.). All the funding sources played no roles in the study.
Project description:ObjectiveCoronavirus disease 2019 (COVID-19) is associated with olfactory dysfunction, but the evolution of the olfactory loss and timeline to recovery are largely unknown. This study examines changes in smell sensitivity in COVID-19-positive (COVID+) and COVID-19-negative (COVID-) viral illness during the initial weeks after infection.Study designCross-sectional cohort comparison.SettingNational anonymous surveys.MethodsSurvey participants were queried about smell sensitivity and general health status at the time of COVID-19 testing and in the weeks that followed.ResultsIn total, 375 (174 COVID+, 201 COVID-) participants completed the survey and 132 (62 COVID+, 70 COVID-) participants completed the 2-week follow-up survey. Normal smell in the COVID+ cohort was less frequent at the time of testing and at follow up (P < .05). Dynamic changes in smell sensitivity in the COVID+ cohort were more frequent in the initial weeks (P < .001). In those with normosmia at the start of infection, 38% of the COVID+ cohort reported worsening smell compared to only 8% in the COVID- cohort (P < .05). Recovery of overall health was associated with normosmia at the time of infection and improvement of smell sensitivity within weeks of infection.ConclusionThe COVID+ cohort showed greater dynamic change in smell sensitivity and a higher rate of persistent olfactory dysfunction in the weeks after infection. Normal smell at the time of COVID-19 infection may still worsen before recovery. Overall health recovery after viral illness is associated with improvement in smell sensitivity and the absence of initial anosmia or hyposmia.
Project description:Non-conductive olfactory dysfunction (OD) is an important extra-pulmonary manifestation of coronavirus disease 2019 (COVID-19). Olfactory bulb (OB) volume loss and olfactory network functional connectivity (FC) defects were identified in two patients suffering from prolonged COVID-19-related OD. One patient received olfactory treatment (OT) by the combination of oral vitamin A and smell training via the novel electronic portable aromatic rehabilitation (EPAR) diffusers. After four-weeks of OT, clinical recuperation of smell was correlated with interval increase of bilateral OB volumes [right: 22.5 mm3 to 49.5 mm3 (120%), left: 37.5 mm3 to 42 mm3 (12%)] and improvement of mean olfactory FC [0.09 to 0.15 (66.6%)].
Project description:Phantosmia has been described as a sense of smell without a true stimulating odor and not been reported with COVID-19 disease. Nine patients admitted to Ear Nose Throat (ENT) Clinic with complaints of a phantom smell sense after an average of 33.5?±?9.5 days after the initial PCR diagnosis. According to the Sniffin 'Sticks test, phantosmia was associated with objective hyposmia in three patients with the persistent phantom smell, and other six patients were detected normosmic. Phantosmia or olfactory hallucinations have not been previously associated with COVID-19 disease. Additionally, COVID-19 related phantosmia showed different characteristics according to described in the literature. Supplementary Information The online version contains supplementary material available at 10.1007/s12070-021-02505-z.
Project description:BackgroundOlfactory dysfunction is a common consequence of COVID-19 infection and persistent symptoms can have a profound impact on quality of life. At present there is little guidance on how best to treat this condition. A variety of interventions have been suggested to promote recovery, including medication and olfactory training. However, it is uncertain whether any intervention is of benefit. This is an update of the 2021 review with one additional study added. OBJECTIVES: 1) To evaluate the benefits and harms of any intervention versus no treatment for people with persisting olfactory dysfunction due to COVID-19 infection. 2) To keep the evidence up-to-date, using a living systematic review approach. SEARCH METHODS: The Cochrane ENT Information Specialist searched the Cochrane ENT Register; Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid Embase; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the latest search was 20 October 2021. SELECTION CRITERIA: We included randomised controlled trials (RCTs) in people with COVID-19 related olfactory disturbance that had persisted for at least four weeks. We included any intervention compared to no treatment or placebo. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were the recovery of sense of smell, disease-related quality of life and serious adverse effects. Secondary outcomes were the change in sense of smell, general quality of life, prevalence of parosmia and other adverse effects (including nosebleeds/bloody discharge). We used GRADE to assess the certainty of the evidence for each outcome.Main resultsWe included two studies with 30 participants. The studies evaluated the following interventions: systemic corticosteroids plus intranasal corticosteroid/mucolytic/decongestant and palmitoylethanolamide plus luteolin. Systemic corticosteroids plus intranasal corticosteroid/mucolytic/decongestant compared to no intervention We included a single RCT with 18 participants who had anosmia for at least 30 days following COVID-19 infection. Participants received a 15-day course of oral corticosteroids combined with nasal irrigation (consisting of an intranasal corticosteroid/mucolytic/decongestant solution) or no intervention. Psychophysical testing was used to assess olfactory function at 40 days. This is a single, small study and for all outcomes the certainty of evidence was very low. We are unable to draw meaningful conclusions from the numerical results. Palmitoylethanolamide plus luteolin compared to no intervention We included a single RCT with 12 participants who had anosmia or hyposmia for at least 90 days following COVID-19 infection. Participants received a 30-day course of palmitoylethanolamide and luteolin or no intervention. Psychophysical testing was used to assess olfactory function at 30 days. This is a single, small study and for all outcomes the certainty of evidence was very low. We are unable to draw meaningful conclusions from the numerical results.Authors' conclusionsThere is very limited evidence available on the efficacy and harms of treatments for persistent olfactory dysfunction following COVID-19 infection. However, we have identified a number of ongoing trials in this area. As this is a living systematic review we will update the data regularly, as new results become available.
Project description:BackgroundEvidence regarding prevalence of COVID-19 related Olfactory dysfunction (OD) among ambulatory patients is highly variable due to heterogeneity in study population and measurement methods. Relatively few studies have longitudinally investigated OD in ambulatory patients with objective methods.MethodsWe performed a longitudinal study to investigate OD among COVID-19 ambulatory patients compared to symptomatic controls who test negative. Out of 81 patients enrolled, 45 COVID-19 positive patients and an age- and sex-matched symptomatic control group completed the BSIT and a questionnaire about smell, taste and nasal symptoms. These were repeated at 1 month for all COVID-19 positive patients, and again at 3 months for those who exhibited persistent OD. Analysis was performed by mixed-effects linear and logistic regression.Results46.7% of COVID-19 patients compared to 3.8% of symptomatic controls exhibited OD at 1-week post diagnosis (p<0.001). At 1 month, 16.7%, (6 of 36), of COVID-19 patients had persistent OD. Mean improvement in BSIT score in COVID-19 patients between 1-week BSIT and 1 month follow-up was 2.0 (95% CI 1.00 - 3.00, p<0.001). OD did not correlate with nasal congestion (r= -0.25, 95% CI, -0.52 to 0.06, p=0.12).ConclusionsAmbulatory COVID-19 patients exhibited OD significantly more frequently than symptomatic controls. Most patients regained normal olfaction by 1 month. The BSIT is a simple validated and objective test to investigate the prevalence of OD in ambulatory patients. OD did not correlate with nasal congestion which suggests a congestion-independent mechanism of OD.