Clinical, sinonasal, and long-term smell and taste outcomes in mildly symptomatic COVID-19 patients

The effect of post-COVID-19 on gustatory and olfactory function: A preliminary case-controlled study

AIMS

The aim of the study was to analyze objective and subjective olfactory/gustatory function in post-COVID-19 infection (PCI).

MATERIALS AND METHODS

Patients with past PCR-confirmed COVID-19 infection and persistent olfactory/gustatory complaints were investigated. Olfactory threshold and identification, gustatory detection, identification, and magnitude scaling were tested.

RESULTS

A total of 42 PCI subjects were compared to 41 age- and gender-matched controls with no COVID-19 history. All PCI tested had mild COVID-19 disease. Mean interval between COVID-19 confirmations to testing was 7.4 ± 3.1 months. PCI subjects complained of combined dysfunction in 85.7%, isolated olfactory or gustatory dysfunction in 7.1% each. Combined complaints were significantly higher in PCI (p < 0.001). Objective testing showed significantly higher prevalence of dysfunction in PCI versus controls for hyposmia (73.8%, 12.2%), anosmia (11.9%, 0%), odor identification (68.5%, 83.0%), hypogeusia (23% and 2.4%, respectively), and impaired magnitude scaling, (p < 0.05). All PCI subjects with hypogeusia had abnormal gustatory magnitude scaling.

CONCLUSIONS

While most PCI subjects complained of combined gustatory and olfactory dysfunction, objective testing showed in the majority an isolated single sense dysfunction, with a low level of agreement between subjective and objective findings. Abnormal objective results for all olfactory and gustatory functions tested may suggest a central rather than peripheral mechanism, although concomitant mechanisms cannot be excluded.

Looking at the Data on Smoking and Post-COVID-19 Syndrome-A Literature Review

Long COVID is a recently described entity that is responsible for significant morbidity and that has consequences ranging from mild to life-threatening. The underlying mechanisms are not completely understood, and treatment options are currently limited, as existing data focus more on risk factors and predictors. Smoking has been reported as a risk factor for poor outcomes of acute SARS-CoV-2 infection and seems to also play a role in mediating post-COVID-19 symptoms. We aimed to review relevant work addressing the interaction between smoking and long COVID in order to characterize smoking's role as a risk factor and possibly identify new research directions. Methods: The PubMed/MEDLINE database was searched using the keywords 'smoking', 'long COVID', and 'post-acute COVID' to identify relevant English-language articles published up to October 2023. Results and conclusions: From the 374 initial hits, a total of 36 papers were deemed relevant to the aim of the review. There was significant variability concerning the ways in which tobacco usage was quantified and reported; still, there is compelling evidence linking smoking to an increased risk of developing manifestations of post-acute-COVID disease. Some clinical conditions, such as dyspnea, cardiovascular symptoms, and cognitive or mental-health impairment, seem to be relatively strongly associated with smoking, while the connection between smoking and upper-airway involvement seems less certain. The available data support recommending smoking cessation as a clinical tool for the prevention of long COVID.

Transient Anosmia and Dysgeusia in COVID-19 Disease: A Cross Sectional Study

Objective

This study aims to explore the prevalence of anosmia and dysgeusia and their impact on COVID-19 patients.

Methods

This is a cross-sectional study. Patients diagnosed with COVID-19 between 1st October 2020 and 30th June 2021 were randomly selected from a national COVID-19 registry. COVID-19 cases were diagnosed using molecular testing method which measured the viral E gene. The Anosmia Reporting Tool, and a brief version of the questionnaire on olfactory disorders were used to measure the outcomes via telephone interviews. Data were analysed using SPSS 27 statistics software.

Results

A total of 405 COVID-19 adults were included in this study, 220 (54.3%) were males and 185 (45.8%) were females. The mean±SD age of participants was 38.2 ± 11.3 years. Alterations in the sense of smell and taste were reported by 206 (50.9%), and 195 (48.1%) of the patients, respectively. Sex and nationality of participants were significantly associated with anosmia and dysgeusia (p < 0.001) and (p-value=0.001) respectively. Among patients who experienced anosmia and dysgeusia, alterations in eating habits (64.2%), impact on mental wellbeing (38.9%), concerns that the alterations were permanent (35.4%), and physical implications and difficulty performing activities of daily living (34%) were reported.

Conclusion

Anosmia and dysgeusia are prevalent symptoms of COVID-19 disease, especially among females. Although transient, anosmia and dysgeusia had considerable impact on patient's life. Neuropsychological implications of COVID-19 in acute infection phase and prognosis of anosmia and dysgeusia in COVID-19 are areas for further exploration.

Taste loss as a distinct symptom of COVID-19: a systematic review and meta-analysis

Chemosensory scientists have been skeptical that reports of COVID-19 taste loss are genuine, in part because before COVID-19 taste loss was rare and often confused with smell loss. Therefore, to establish the predicted prevalence rate of taste loss in COVID-19 patients, we conducted a systematic review and meta-analysis of 376 papers published in 2020-2021, with 235 meeting all inclusion criteria. Drawing on previous studies and guided by early meta-analyses, we explored how methodological differences (direct vs. self-report measures) may affect these estimates. We hypothesized that direct measures of taste are at least as sensitive as those obtained by self-report and that the preponderance of evidence confirms taste loss is a symptom of COVID-19. The meta-analysis showed that, among 138,015 COVID-19-positive patients, 36.62% reported taste dysfunction (95% confidence interval: 33.02%-40.39%), and the prevalence estimates were slightly but not significantly higher from studies using direct (n = 15) versus self-report (n = 220) methodologies (Q = 1.73, df = 1, P = 0.1889). Generally, males reported lower rates of taste loss than did females, and taste loss was highest among middle-aged adults. Thus, taste loss is likely a bona fide symptom of COVID-19, meriting further research into the most appropriate direct methods to measure it and its underlying mechanisms.

Short and Long-Term Wellbeing of Children following SARS-CoV-2 Infection: A Systematic Review

Post-COVID conditions in children and adolescents were mostly investigated as the incidence of individual or clusters of symptoms. We aimed to describe the findings of studies assessing key outcomes related to global wellbeing and recovery in children and adolescents from a public health perspective. We searched the Cochrane COVID-19 Study Register and WHO COVID-19 Global literature on coronavirus disease database on 5 November 2021 and tracked ongoing studies published after this date. We included observational studies on children and adolescents with a follow-up greater than 12 weeks and focused on the outcomes of quality of life, recovery/duration of symptoms, school attendance and resource use/rehabilitation. We assessed their methodological quality, and we prepared a narrative synthesis of the results. We included 21 longitudinal and 4 cross-sectional studies (6 with a control group) with over 68 thousand unvaccinated children and adolescents with mostly asymptomatic or mild disease. Study limitations included convenience sampling, a poor description of their study population and heterogeneous definitions of outcomes. Quality of life was not largely affected in adolescents following COVID-19, but there might be greater impairment in young children and in those with more severe forms of the disease (4 studies). There might also be an impairment in daily activities and increased school absenteeism following COVID-19, but the findings were heterogeneous (5 studies). A total of 22 studies provided highly variable estimates based on heterogeneous definitions of overall persistence of symptoms (recovery), ranging from 0 to 67% at 8-12 weeks and 8 to 51% at 6-12 months. We found limited data on resource use and the need for rehabilitation. One controlled study indicated that the quality of life of infected children and adolescents might not substantially differ from controls. All controlled studies found a higher burden of persistent symptoms in COVID-19 cases compared with test-negative controls or cases of influenza. There is limited evidence on the short and long-term well-being of children following SARS-CoV-2 infection. High-quality longitudinal studies with control groups are needed to describe the outcomes in this population, especially in vaccinated children and those affected by new variants of the virus.

Physiological discrimination and correlation between olfactory and gustatory dysfunction in long-term COVID-19

The spread of the SARS-CoV-2 virus produces a new disease termed COVID-19, the underlying physiological mechanisms of which are still being understood. Characteristic of the infection is the compromising of taste and smell. There is a persistent need to discriminate the dysfunctions and correlation between taste and smell, which are probably epiphenomena of other concealed conditions. Anosmic and ageusic long-term COVID-19 patients were re-evaluated after 1 year using a Volabolomic approach with an e-nose recording system coupled with olfactometric and gustometric tests. Here a range of sensory arrangements was found, from normal taste and smell to complete losses. The following patterns of olfactory threshold (OT)-taste threshold-olfactory uni- and cross-modal perception were found anosmia-severe hypogeusia-anosmia; hyposmia-hypogeusia-severe hyposmia; normosmia-ageusia-hyposmia; severe hyposmia -normogeusia-normosmia. There is a strong correlation between OT and olfactory uni- and cross-modal perception, a moderate correlation between olfactory and taste threshold and no correlation between OT and taste threshold. In conclusion, this study provides evidence for the feasibility of testing the chemical senses to directly objectify function in order to discriminate taste from olfactory impairment. Furthermore, it allows to hypothesize a long-term effect of the virus due to neuroinvasion through, probably, the olfactory system with injury in the related multisensory areas of taste and smell.

Taste loss as a distinct symptom of COVID-19: a systematic review and meta-analysis

Chemosensory scientists have been skeptical that reports of COVID-19 taste loss are genuine, in part because before COVID-19 taste loss was rare and often confused with smell loss. Therefore, to establish the predicted prevalence rate of taste loss in COVID-19 patients, we conducted a systematic review and meta-analysis of 376 papers published in 2020-2021, with 241 meeting all inclusion criteria. Drawing on previous studies and guided by early meta-analyses, we explored how methodological differences (direct vs. self-report measures) may affect these estimates. We hypothesized that direct measures of taste are at least as sensitive as those obtained by self-report and that the preponderance of evidence confirms taste loss is a symptom of COVID-19. The meta-analysis showed that, among 138,897 COVID-19-positive patients, 39.2% reported taste dysfunction (95% confidence interval: 35.34%-43.12%), and the prevalence estimates were slightly but not significantly higher from studies using direct (n = 18) versus self-report (n = 223) methodologies (Q = 0.57, df = 1, P = 0.45). Generally, males reported lower rates of taste loss than did females, and taste loss was highest among middle-aged adults. Thus, taste loss is likely a bona fide symptom of COVID-19, meriting further research into the most appropriate direct methods to measure it and its underlying mechanisms.

Factors associated with anosmia recovery rate in COVID-19 patients

Objectives

The present study aimed to assess the 4- and 8-week recovery rate of anosmia and determine the factors associated with recovery in COVID-19 patients.

Method

This retrospective study was conducted from December 2020 to March 2021. RT-PCR-proven COVID-19 adult patients (over 18 years of age) with a positive history of anosmia were included in this study. Anosmia was assessed based on the COVID-19 Anosmia Reporting Tool. The recovery rate of anosmia after 4 and 8 weeks were evaluated, and the relationship between the patients' recovery and their clinical and demographic data was assessed.

Results

A total of 235 patients were included. Their mean age (±SD) was 43.95 ± 15.27 years. Anosmia recovery was reported in 207(88.51%) and 219 (93.19%) participants till 4 and 8 weeks. The mean recovery time was 19.42 ± 8.81 days. The result of logistic regression showed that smoking (P = .031; OR = 10.813), ageusia (P = .002; OR = 5.340), headache (P = .006; OR = 0.243), and nasal discharge (P < .001; OR = 0.080) were significantly associated with 4 weeks anosmia recovery. The only risk factor which was associated with a lower rate of 8 weeks anosmia recovery was presence of nasal discharge (OR = 0.106, P = .002).

Conclusion

The only risk factor which was associated with a lower rate of 8 weeks anosmia recovery was presence of nasal discharge. Our result demonstrated that although smoking was associated with higher recovery rate till 4 weeks, it could not be considered as a protective factor after 8 weeks. More studies are recommended to investigate the relationship between anosmia and the associated factors by consideration of both short- and long-term recovery rates and assess the possible mechanisms that could justify this association.

Levels of Evidence

3b.

Taste loss as a distinct symptom of COVID-19: A systematic review and meta-analysis

Chemosensory scientists have been skeptical that reports of COVID-19 taste loss are genuine, in part because before COVID-19, taste loss was rare and often confused with smell loss. Therefore, to establish the predicted prevalence rate of taste loss in COVID-19 patients, we conducted a systematic review and meta-analysis of 376 papers published in 2020-2021, with 241 meeting all inclusion criteria. Additionally, we explored how methodological differences (direct vs. self-report measures) may affect these estimates. We hypothesized that direct prevalence measures of taste loss would be the most valid because they avoid the taste/smell confusion of self-report. The meta-analysis showed that, among 138,897 COVID-19-positive patients, 39.2% reported taste dysfunction (95% CI: 35.34-43.12%), and the prevalence estimates were slightly but not significantly higher from studies using direct (n = 18) versus self-report (n = 223) methodologies (Q = 0.57, df = 1, p = 0.45). Generally, males reported lower rates of taste loss than did females and taste loss was highest in middle-aged groups. Thus, taste loss is a bona fide symptom COVID-19, meriting further research into the most appropriate direct methods to measure it and its underlying mechanisms.