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Background: Interleukin 6 (IL-6) is a proinflammatory cytokine that is secreted by cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it is widely recognized as a negative prognostic factor. The purpose of this study was to analyze the correlations between the olfactory scores determined by psychophysical tests and the serum levels of IL-6 in patients affected by coronavirus disease 2019 (COVID-19) Methods: Patients underwent psychophysical olfactory assessment with Connecticut Chemosensory Clinical Research Center test and IL-6 plasma level determination within 10 days of the clinical onset of COVID-19. Results: Seventy-four COVID-19 patients were included in this study. COVID-19 staged as mild in 34 patients, moderate in 26 and severe in 14 cases. There were no significant differences in olfactory scores across the different COVID-19 severity groups. In the patient series, the median plasma level of IL-6 was 7.7 pg/mL (IQR 3.7–18.8). The concentration of IL-6 was found to be significantly correlated with the severity of COVID-19 with a directly proportional relationship. The correlation between IL-6 plasma concentrations and olfactory scores was weak (rs = 0.182) and not significant (p = 0.12). Conclusions: In COVID-19 patients, psychophysical olfactory scores did not show significant correlations with the plasma levels of a well-recognized negative prognostic factor such as IL-6. This observation casts some shadows on the positive prognostic value of olfactory dysfunctions. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to estimate the 1 year prevalence and recovery rate of self-reported chemosensory dysfunction in a series of subjects with previous mild-to-moderate symptomatic COVID-19. Methods: Prospective study based on the SNOT-22, item "sense of smell or taste" and additional outcomes. Results: 268/315 patients (85.1%) completing the survey at baseline also completed the follow-up interview. The 12 months prevalence of self-reported COVID-19 associated chemosensory dysfunction was 21.3% (95% CI 16.5–26.7%). Of the 187 patients who complained of COVID-19 associated chemosensory dysfunction at baseline, 130 (69.5%; 95% CI 62.4–76.0%) reported complete resolution of smell or taste impairment, 41 (21.9%) reported a decrease in the severity, and 16 (8.6%) reported the symptom was unchanged or worse 1 year after onset. The risk of persistence was higher for patients reporting a baseline SNOT-22 score ≥ 4 (OR = 3.32; 95% CI 1.32–8.36) as well as for those requiring ≥ 22 days for a negative swab (OR = 2.18; 95% CI 1.12–4.27). Conclusion: A substantial proportion of patients with previous mild-to-moderate symptomatic COVID-19 characterized by new onset of chemosensory dysfunction still complained on altered sense of smell or taste 1 year after the onset. [ABSTRACT FROM AUTHOR]

Background: From the start of the pandemic, many European otolaryngologists observed an unprecendented number of anosmic patients. Early reports proposed that anosmia could be the first or even the only symptom of COVID-19 infection, prompting calls for self-isolation in affected patients. Methods: In the present article, we review the COVID-19 anosmia literature and try to answer the following two questions: first, why is COVID-19 infection responsible for such a high incidence of anosmia? Second, in patients with more severe forms is anosmia really less prevalent and why? Results: In terms of the etiology of olfactory dysfunction, several hypotheses were proposed at the outset of the pandemic; that olfactory cleft inflammation and obstruction caused a localized conductive loss, that there was injury to the sustentacular supporting cells in the olfactory epithelium or, given the known neurotropic potential of coronavirus, that the virus could invade and damage the olfactory bulb. Olfactory cleft obstruction may contribute to the olfactory dysfunction in some patients, perhaps most likely in those that show very early resolution, it cannot account for the loss in all patients. Moreover, disordered regrowth and a predominance of immature neurons have been shown to be associated with parosmia, which is a common finding amongst patients with Covid-related anosmia. A central mechanism therefore certainly seems to be consistent with the group of patients with more prolonged olfactory deficits. Sustentacular cells showing ACE-2 immunohistochemical expression 200 to 700 times greater than nasal or tracheal epithelia seem to be the main SARS-CoV-2 gateway. As the pathophysiology of COVID-19 anosmia seems to be better understood, the question of why patients with a moderate to severe form of COVID-19 infection have less olfactory involvement remains unresolved. Different potential explanations are discussed in this review. Conclusions : The last 5 months have benefited from great international collaborative research, first highlighting and then proving the value of loss of smell and taste as a symptom of COVID-19. Adoption of loss of smell into the case definition by international public health bodies will facilitate control of disease transmission. [ABSTRACT FROM AUTHOR]