Smell disorders are commonly reported with COVID-19 infection. Some patients show prolonged smell-related issues, even after the respiratory symptoms are resolved. To explore the concerns of patients, and to provide an overview for each specific smell disorder, we explored the longitudinal survey that was conducted by 1, and contained self-reports on the changes of smell that participants experienced at two time points. People who still suffered from smell disorders at the second time point, hence named longhaulers, were compared to those who were not, hence named non-longhaulers. Specifically, three aims were pursued in this study. First, to classify smell disorders based on the participants self-reports. Second, to classify the sentiment of each self-report using a machine learning approach, and third, to find specific keywords that best describe the smell dysfunction in those self-reports. We found that the prevalence of parosmia and hyposmia was higher in longhaulers than in non-longhaulers. Furthermore, the results suggest that longhaulers stated self-reports with more negative sentiment than non-longhaulers. Finally, we found specific keywords that were more typical for either longhaulers compared to non-longhaulers. Taken together, our work shows consistent findings with previous studies, while at the same time, provides new insights for future studies investigating smell disorders.

The authors have declared no competing interest.

this study did not receive any funding

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This work has been designed and planned following the structure of a survey and used data previously available to the GCCR that analyzed the closed-ended responses. More specifically, we used data acquired by means of open-ended questions included in those surveys. The existing protocol complies with the revised Declaration of Helsinki and was approved as an exempt study by the Office of Research Protections at The Pennsylvania State University (PennState) in the United States (STUDY00014904). see also: 2. Parma V, Ohla K, Veldhuizen MG, et al. More Than Smell-COVID-19 Is Associated With Severe Impairment of Smell, Taste, and Chemesthesis. Chem Senses. 2020;45(7):609-622. doi:10.1093/chemse/bjaa041 3. Gerkin RC, Ohla K, Veldhuizen MG, et al. Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms. Chem Senses. 2021;46:bjaa081. doi:10.1093/chemse/bjaa081

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The pre-registration of our analyses, as well as all data and analysis scripts associated with this manuscript can be found at OSF.io (https://osf.io/xv6mn/). This analysis was done as part of the Global Consortium for Chemosensory Research (https://gcchemosensr.org/).

https://osf.io/xv6mn/