Giving a voice to adults with COVID-19: An analysis of open-ended comments from smell longhaulers and non-longhaulers (preprint)

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.

Increasing incidence of parosmia and phantosmia in patients recovering from COVID-19 smell loss (preprint)

ImportanceSudden smell loss is a specific early symptom of COVID-19, with an estimated prevalence of ~40% to 75%. Smell impairment affects physical and mental health, and dietary behavior. Thus, it is critical to understand the rate and time course of smell recovery. ObjectiveTo characterize smell function and recovery up to 11 months post COVID-19 infection. Settings, ParticipantsThis 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 respiratory symptoms, chemosensory function and COVID-19 diagnosis survey (S1) between April and September 2020 and completed 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. Main Outcomes & MeasuresPrimary outcomes are ratings of smell and taste function on a visual analog scale, and self-report of parosmia (smell distortions) and phantosmia (unexplained smells). Secondary outcomes include a checklist of other COVID-19 symptoms. ResultsOn 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. During COVID-19 illness, the ability to smell was slightly lower among those who did not recover their pre-illness ability to smell at S2. Conclusions and RelevanceWhile smell loss improves for many individuals who lost it due to COVID-19, the prevalence of parosmia and phantosmia increases substantially over time. Olfactory dysfunction is also associated with wider COVID-19 symptoms and may persist for many months after COVID-19 onset. 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 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. Trial registrationThis project was pre-registered at OSF: https://osf.io/3e6zc. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/21262763v2_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@b2aceforg.highwire.dtl.DTLVardef@77a539org.highwire.dtl.DTLVardef@1004dbborg.highwire.dtl.DTLVardef@ef5c9c_HPS_FORMAT_FIGEXP M_FIG C_FIG Key PointsO_ST_ABSQuestionC_ST_ABSWhat are the characteristics of smell and taste recovery of COVID-19 patients? FindingsIn this preregistered observational study of 1,468 participants, smell loss is associated with a higher number of COVID-19 symptoms, and may persist for at least 11 months following disease onset. While a majority of participants report quantitative improvement in their ability to smell, the prevalence of parosmia and phantosmia increases substantially at follow-up. Taste recovers faster than smell, suggesting taste and smell recover separately and can be distinguished by the respondents. MeaningOlfactory dysfunction appears to be a component of long-COVID, with parosmia as a prominent symptom in almost half of those with smell loss. More research into treatment is needed, especially given that olfactory dysfunction is associated with depression and loss of appetite. Health professionals should be aware of these common and long lasting effects.

More than just smell - COVID-19 is associated with severe impairment of smell, taste, and chemesthesis (preprint)

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, generally lacked quantitative measurements, were mostly restricted to data from single countries. Here, we report the development, implementation and initial results of a multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, 8 other, ages 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change+/-100) revealed a mean reduction of smell (-79.7+/- 28.7, mean+/- SD), taste (-69.0+/- 32.6), and chemesthetic (-37.3+/- 36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis. The multimodal impact of COVID-19 and lack of perceived nasal obstruction suggest that SARS-CoV-2 infection may disrupt sensory-neural mechanisms.