ABSTRACT
BACKGROUND: Sudden smell loss is a specific early symptom of COVID-19, which, prior to the emergence of Omicron, had estimated prevalence of ~40% to 75%. Chemosensory impairments affect physical and mental health, and dietary behavior. Thus, it is critical to understand the rate and time course of smell recovery. The aim of this cohort study was to characterize smell function and recovery up to 11 months post COVID-19 infection. METHODS: This longitudinal survey of individuals suffering COVID-19-related smell loss assessed disease symptoms and gustatory and olfactory function. Participants (n=12,313) who completed an initial survey (S1) about respiratory symptoms, chemosensory function and COVID-19 diagnosis between April and September 2020, were invited to complete a follow-up survey (S2). Between September 2020 and February 2021, 27.5% participants responded (n=3,386), with 1,468 being diagnosed with COVID-19 and suffering co-occurring smell and taste loss at the beginning of their illness. RESULTS: At follow-up (median time since COVID-19 onset ~200 days), ~60% of women and ~48% of men reported less than 80% of their pre-illness smell ability. Taste typically recovered faster than smell, and taste loss rarely persisted if smell recovered. Prevalence of parosmia and phantosmia was ~10% of participants in S1 and increased substantially in S2: ~47% for parosmia and ~25% for phantosmia. Persistent smell impairment was associated with more symptoms overall, suggesting it may be a key marker of long-COVID illness. The ability to smell during COVID-19 was rated slightly lower by those who did not eventually recover their pre-illness ability to smell at S2. CONCLUSIONS: While smell ability improves for many individuals who lost it during acute COVID-19, the prevalence of parosmia and phantosmia increases substantially over time. Olfactory dysfunction is associated with broader persistent symptoms of COVID-19, and may last for many months following acute COVID-19. Taste loss in the absence of smell loss is rare. Persistent qualitative smell symptoms are emerging as common long-term sequelae; more research into treatment options is strongly warranted given that even conservative estimates suggest millions of individuals may experience parosmia following COVID-19. Healthcare providers worldwide need to be prepared to treat post COVID-19 secondary effects on physical and mental health.
ABSTRACT
In early March of 2020, reports appeared in the social media of many countries linking smell/taste loss to the spread of SARS-CoV-2. Such reports led to studies of the prevalence and reversibility of the smell loss of COVID-19 and the cellular mechanisms responsible for the loss. These studies have the potential to play a significant role in early COVID-19 detection and the development of preventative interventions and therapies for COVID-19. In this symposium, the olfactory and gustatory manifestations of COVID-19 will be reviewed. Dr. Parma will discuss how a global consortium approached this issue in COVID-19 patients in over 60 countries. She will address the prevalence of chemosensory loss and its continued presence in various groups of patients. Dr. Overdevest will present the evolution in investigations to identify molecular pathways that are dysregulated during COVID-19 infection through a histopathologic and transcriptomic evaluation of post-mortem nasal epithelium biopsies.As the pandemic continues despite containment and mitigation strategies, even a low percentage of patients with sustained smell loss and other problems may challenge health systems. Dr. Yan will discuss the implications of smell loss, its assessment, and its management in the clinic. Moreover, challenges for clinicians to minimize its long-term effects on physical and mental health, including quality of life, will be addressed.Finally, Dr. Doty will explain how machine learning techniques are being used to optimize the sensitivity of smell tests to detect COVID-19. Such tests have the potential to provide a sensitive and inexpensive means for detecting persons carrying SARS-CoV-2 early in the COVID-19 disease process, as well as for tracking their function over time.
ABSTRACT
COVID-19, a rapidly spreading disease due to the SARSCoV- 2 virus, is continuing to cause a staggering loss of life and an overwhelming impact on families and economies throughout the world. Among the expressed symptoms of COVID-19, it is now well established that sudden decreased smell function is present early in the disease process of most patients with COVID-19, even occurring before the onset of fever, cough, headache, and shortness of breath in many cases. Here, we used a brief scratch and sniff smell test with 8 odorants along with PCR testing on 400 subjects who were screened for COVID-19. The results showed an area under the curve of 0.87 with a sensitivity of 0.90 and specificity of 0.37. This supports the potential of low cost quick smell tests for identifying the subjects infected by SARS-CoV-2.