Gustatory Dysfunction: A Highly Specific and Smell-Independent Symptom of COVID-19

Clinical Profile and Outcome Analysis of Ear-Nose-Throat Symptoms in SARS-CoV-2 Omicron Subvariant Infections

Objective: This study aimed to investigate the clinical characteristics and outcomes of ear-nose-throat (ENT) symptoms in SARS-CoV-2 Omicron infected patients resulting from local transmission. Methods: A convenience sampling network survey was conducted among individuals infected with SARS-CoV-2 to examine the characteristics and progression of ENT symptoms associated with local transmission. The survey comprised 52 questions, and univariable and multivariable logistic regression analyses were employed to assess the rate, severity, and outcome of ENT symptoms across different genders and age groups. Results: Among the 1,366 individuals included in the investigation, a peak in new infections occurred on 20th December, and the majority (78.4%) were female. The most common symptoms reported were coughing (90.6%), nasal congestion (77.2%), and runny nose (74.3%). Otologic symptoms were predominantly represented by tinnitus (29.7%). Conclusion: The rate of specific symptoms showed a significant correlation with age and gender. It is crucial to provide timely medical intervention, especially for female patients. This study offers a comprehensive understanding of the symptom spectrum in individuals infected with the virus, providing valuable insights for the development of targeted symptom management strategies.

Transient loss and recovery of oral chemesthesis, taste and smell with COVID-19: a small case-control series

Anosmia is common with respiratory virus infections, but loss of taste or chemesthesis is rare. Reports of true taste loss with COVID-19 were viewed skeptically until confirmed by multiple studies. Nasal menthol thresholds are elevated in some with prior COVID-19 infections, but data on oral chemesthesis are lacking. Many patients recover quickly, but precise timing and synchrony of recovery are unclear. Here, we collected broad sensory measures over 28 days, recruiting adults (18-45 years) who were COVID-19 positive or recently exposed (close contacts per U.S. CDC criteria at the time of the study) in the first half of 2021. Participants received nose clips, red commercial jellybeans (Sour Cherry and Cinnamon), and scratch-n-sniff cards (ScentCheckPro). Among COVID-19 cases who entered the study on or before Day 10 of infection, Gaussian Process Regression showed odor identification and odor intensity (two distinct measures of function) each declined relative to controls (close contacts who never developed COVID-19), but effects were larger for intensity than identification. To assess changes during early onset, we identified four COVID-19 cases who enrolled on or prior to Day 1 of their illness â€" this allowed for visualization of baseline ratings, loss, and recovery of function over time. Four controls were matched for age, gender, and race. Variables included sourness and sweetness (Sour Cherry jellybeans), oral burn (Cinnamon jellybeans), mean orthonasal intensity of four odors (ScentCheckPro), and perceived nasal blockage. Data were plotted over 28 days, creating panel plots for the eight cases and controls. Controls exhibited stable ratings over time. By contrast, COVID-19 cases showed sharp deviations over time. No single pattern of taste loss or recovery was apparent, implying different taste qualities might recover at different rates. Oral burn was transiently reduced for some before recovering quickly, suggesting acute loss may be missed in data collected after acute illness ends. Changes in odor intensity or odor identification were not explained by nasal blockage. Collectively, intensive daily testing shows orthonasal smell, oral chemesthesis and taste were each altered by acute COVID-19 infection, and this disruption was dyssynchronous for different modalities, with variable loss and recovery rates across modalities and individuals.

Covid-19 affects taste independent of taste-smell confusions: results from a combined chemosensory home test and online survey from a large global cohort

People often confuse smell loss with taste loss, so it is unclear how much gustatory function is reduced in patients self-reporting taste loss. Our pre-registered cross-sectional study design included an online survey in 12 languages with instructions for self-administering chemosensory tests with 10 household items. Between June 2020 and March 2021, 10,953 individuals participated. Of these, 5,225 self-reported a respiratory illness and were grouped based on their reported COVID test results: COVID-positive (COVID+, N = 3,356), COVID-negative (COVID-, N = 602), and COVID unknown for those waiting for a test result (COVID?, N = 1,267). The participants who reported no respiratory illness were grouped by symptoms: sudden smell/taste changes (STC, N = 4,445), other symptoms excluding smell or taste changes (OthS, N = 832), and no symptoms (NoS, N = 416). Taste, smell, and oral irritation intensities and self-assessed abilities were rated on visual analog scales. Compared to the NoS group, COVID+ was associated with a 21% reduction in taste (95% confidence interval (CI): 15-28%), 47% in smell (95% CI: 37-56%), and 17% in oral irritation (95% CI: 10-25%) intensity. There were medium to strong correlations between perceived intensities and self-reported abilities (r = 0.84 for smell, r = 0.68 for taste, and r = 0.37 for oral irritation). Our study demonstrates that COVID-19-positive individuals report taste dysfunction when self-tested with stimuli that have little to none olfactory components. Assessing the smell and taste intensity of household items is a promising, cost-effective screening tool that complements self-reports and may help to disentangle taste loss from smell loss. However, it does not replace standardized validated psychophysical tests.

COVID-19 neuropsychiatric repercussions: Current evidence on the subject

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has affected the entire world, causing the coronavirus disease 2019 (COVID-19) pandemic since it was first discovered in Wuhan, China in December 2019. Among the clinical presentation of the disease, in addition to fever, fatigue, cough, dyspnea, diarrhea, nausea, vomiting, and abdominal pain, infected patients may also experience neurological and psychiatric repercussions during the course of the disease and as a post-COVID-19 sequelae. Thus, headache, dizziness, olfactory and gustatory dysfunction, cerebrovascular disorders, neuromuscular abnormalities, anxiety, depression, and post-traumatic stress disorder can occur both from the infection itself and from social distancing and quarantine. According to current evidence about this infection, the virus has the ability to infect the central nervous system (CNS) via angiotensin-converting enzyme 2 (ACE2) receptors on host cells. Several studies have shown the presence of ACE2 in nerve cells and nasal mucosa, as well as transmembrane serine protease 2, key points for interaction with the viral Spike glycoprotein and entry into the CNS, being olfactory tract and blood-brain barrier, through hematogenous dissemination, potential pathways. Thus, the presence of SARS-CoV-2 in the CNS supports the development of neuropsychiatric symptoms. The management of these manifestations seems more complex, given that the dense parenchyma and impermeability of brain tissue, despite protecting the brain from the infectious process, may hinder virus elimination. Still, some alternatives used in non-COVID-19 situations may lead to worse prognosis of acute respiratory syndrome, requiring caution. Therefore, the aim of this review is to bring more current points related to this infection in the CNS, as well as the repercussions of the isolation involved by the pandemic and to present perspectives on interventions in this scenario.

Frequency and Severity of Ear-Nose-Throat (ENT) Symptoms during COVID-19 Infection

Background and Objectives: Coronavirus disease 2019 (COVID-19) is a new disease entity caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The main symptoms of infection at the onset of the pandemic include dyspnea, cough and high fever. Ear−nose−throat (ENT) symptoms are among the ones presented by patients in the course of infection. The aim of the study was to analyze the frequency of ENT symptoms and to assess their severity and duration in COVID-19 patients. Materials and Methods: The study included 337 patients who had been infected with SARS-CoV-2, as confirmed by a PCR test. The study participants were >18 years old; the mean age was 43.98 years ± 13.47 SD. The convalescents completed a questionnaire that contained 26 questions, including 9 detailed questions related to ENT symptoms, such as sore throat, vertigo, dizziness, hearing disorders, olfactory disorders, taste disturbance, headache, cough and dyspnea. The severity of symptoms was assessed using a Visual Analogue Scale (VAS). Results: The most reported ENT symptoms were olfactory disorders, which occurred in 72% of patients. The second most frequent symptom was taste disturbance (68%), VAS = 6.79 ± 3.01. Vertigo and dizziness were reported by 34% of respondents (VAS = 4.01 ± 2.01). Tinnitus was observed in 15% of patients, VAS = 3.87 ± 1.98; 14% of the subjects reported hearing impairment (VAS = 3.81 ± 2.37). Conclusions: Symptoms related to the sense of smell, taste and hearing are some of the most common symptoms in the course of COVID-19, which is important in the therapeutic and epidemiological management of patients. Delayed diagnosis and treatment of symptoms, especially those related to the hearing organ, may result in greater permanent damage.

Morphological and Immunopathological Aspects of Lingual Tissues in COVID-19

COVID-19, a recently emerged disease caused by SARS-CoV-2 infection, can present with different degrees of severity and a large variety of signs and symptoms. The oral manifestations of COVID-19 often involve the tongue, with loss of taste being one of the most common symptoms of the disease. This study aimed to detect SARS-CoV-2 RNA and assess possible morphological and immunopathological alterations in the lingual tissue of patients who died with a history of SARS-CoV-2 infection. Sixteen cadavers from 8 SARS-CoV-2 positive (COVID-19+) and 8 negative (COVID-19−) subjects provided 16 tongues, that were biopsied. Samples underwent molecular analysis through Real-Time RT-PCR for the detection of SARS-CoV-2 RNA. Lingual papillae were harvested and processed for histological analysis and for immunohistochemical evaluation for ACE2, IFN-γ and factor VIII. Real-Time RT-PCR revealed the presence of SARS-CoV-2 RNA in filiform, foliate, and circumvallate papillae in 6 out of 8 COVID-19+ subjects while all COVID-19− samples resulted negative. Histology showed a severe inflammation of COVID-19+ papillae with destruction of the taste buds. ACE2 and IFN-γ resulted downregulated in COVID-19+ and no differences were evidenced for factor VIII between the two groups. The virus was detectable in most COVID-19+ tongues. An inflammatory damage to the lingual papillae, putatively mediated by ACE2 and IFN-γ in tongues from COVID-19+ cadavers, was observed. Further investigations are needed to confirm these findings and deepen the association between taste disorders and inflammation in SARS-CoV-2 infection.

How common are taste and smell abnormalities in COVID-19? A systematic review and meta-analysis

OBJECTIVE

Olfactory and gustatory dysfunction (OGD) are important early clinical symptoms of COVID-19. We aim to calculate the pooled prevalence of these symptoms and discuss the likely implications on clinical practice such as their use as screening tools and potential prognosis indicators.

METHODS

Using a combination of keywords and medical subject headings, we searched for observational studies in the following five databases: Medline/PubMed, Scopus, Cochrane Library, Web of Science, and Google Scholar. Two authors independently screened and selected the final articles according to the inclusion criteria. Two investigators independently assessed the risk of bias in individual studies using the Newcastle-Ottawa Scale. Heterogeneity and publication bias were also assessed. The reported outcome of the pooled analysis was the prevalence of OGD calculated using a random-effect model. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to report results.

RESULTS

Seventeen studies with a total sample size of 4149 were included in this meta-analysis. Out of these, 2106 and 2676 patients reported some degree of olfactory and/or gustatory dysfunction with COVID-19, respectively. The reported outcomes were in terms of pooled prevalence, with gustatory dysfunction being 57.33% and olfactory dysfunction being 59.69%, a significantly high occurrence.

CONCLUSION

There is a high occurrence of smell and taste impairment in COVID-19. Given the lack of objective testing for detecting OGD in most studies, the high prevalence found is likely to be an underestimation of the true prevalence. This implies that physicians must use them as reliable early indicators of COVID-19 and employ them before using expensive tests.

The Effects of Persistent Olfactory and Gustatory Dysfunctions on Quality of Life in Long-COVID-19 Patients

(1) Background: Persistent olfactory (POD) and gustatory (PGD) dysfunctions are one of the most frequent symptoms of long-Coronavirus Disease 2019 but their effect on the quality of life (QoL) of patients is still largely unexplored. (2) Methods: An online survey was administered to individuals who reported to have had SARS-CoV-2 infection at least 6 months prior with persisting COVID-19 symptoms (using the COVID symptom index), including ratings of POD and PGD, and their physical (PCS) and mental (MCS) components of quality of life were assessed using the standardized short form 12 questionnaire (SF-12). (3) Results: Responses from 431 unique individuals were included in the analyses. The most frequent persistent symptoms were: fatigue (185 cases, 42.9%), olfactory dysfunction (127 cases, 29.5%), gustatory dysfunction (96 cases, 22.3%) and muscle pain (83 cases, 19.3%). Respondents who reported persisting muscle pain, joint pain, fatigue, headache, gastrointestinal disturbances, and dyspnea had significantly worse PCS. Those experiencing persistent fatigue and dyspnea also showed significantly lower MCS. Respondents reporting POD or PGD showed significantly worse QoL, but only pertaining to the MCS. Multiple regressions predicted MCS based on olfactory and marginally on gustatory ratings, but not PCS. Age significantly affected the prediction of PCS but not MCS, and gender and temporal distance from the COVID-19 diagnosis had no effect. (4) Conclusions: POD and PGD are frequent symptoms of the long-COVID-19 syndrome and significantly reduce QoL, specifically in the mental health component. This evidence should stimulate the establishment of appropriate infrastructure to support individuals with persistent CD, while research on effective therapies scales up.

Clinical Presentation of the SARS-CoV-2 Virus Infection and Predictive Validity of the PCR Test in Primary Health Care Worker Patients of the Spanish National Health System

Background: Despite the impact that the SARS-CoV-2 virus infection has presented in Spain, data on the diagnostic capacity of the symptoms associated with this infection are limited, especially among patients with mild symptoms and who are detected in the primary care field (PC). The objective of the present study was to know the associated symptoms and their predictive criterial validity in SARS-CoV-2 infection among professionals working in PC. Methods: A cross-sectional, multicenter study was carried out in the Spanish National Health System, through an epidemiological survey directed to patients who underwent the PCR test for SARS-CoV-2 in the PC setting. Results: A total of 1612 patients participated, of which 86.6% were PC healthcare professionals, and of these, 67.4% family doctors. Hyposmia, with a sensitivity of 42.69% (95% CI: 37.30–48.08) and a specificity of 95.91% (95% CI: 94.78–97.03), and ageusia with a sensitivity of 39.47% (34.15–44.80) and a specificity of 95.20% (93.98–96.41) were the symptoms with the highest criteria validity indexes. Conclusions: This study identifies the specific symptoms of loss of smell or taste as the most frequently associated with SARS-CoV-2 infection, essential in the detection of COVID-19 given its high frequency and predictive capacity.

High prevalence of long-term olfactory dysfunction confirmed by olfactory testing after a community COVID-19 outbreak

Purpose

The prevalence of long-term olfactory and gustatory dysfunction in participants suffering from sudden chemosensory loss due to coronavirus disease 2019 (COVID-19) is unknown. Furthermore, evaluations of the reliability of participants’ self-reporting of olfactory function (SOF) and gustatory function (SGF) using extended objective psychophysical testing are missing.

Methods

In this population-based cohort study in a PCR-tested community in Thuringia, Germany, olfactory function was extensively examined 4 months after a COVID-19 outbreak using the “Sniffin Sticks” test battery to determine the TDI_a score, i.e., the sum of results obtained for threshold, discrimination, and identification scores averaged for both nasal sides. Gustatory function was assessed using the three-drop test resulting in the gustatory composite score (CS_g). The data were compared with SOF and SGF.

Results

Of 43 adult convalescents (median age: 68 years; 58% female) after SARS-CoV‑2 infection, 18 participants (42%) had olfactory complaints due to SOF, one participant (2%) complained of taste disturbance due to SGF. The TDI_a was 22.0 ± 5.9. Normosmia, hyposmia, and anosmia were seen in 17, 18, and eight participants, respectively. TDI_a correlated with SOF (r_s = −0.434, p = 0.004); CS_g was 23.5 ± 2.7. Normogeusia and hypogeusia were objectified in 39 and four participants, respectively. The prevalence of long-term olfactory dysfunction and gustatory dysfunction in the study group was 60.5 and 9.3%, respectively.

Conclusion

The SOF was reliable, especially for participants who felt a sudden chemosensory dysfunction during the outbreak. At 4 months after SARS-CoV‑2 infection, a high proportion of participants were dysosmic, whereas nearly all of them had normal taste function.

Massively collaborative crowdsourced research on COVID19 and the chemical senses: Insights and outcomes

In March 2020, the Global Consortium of Chemosensory Research (GCCR) was founded by chemosensory researchers to address emerging reports of unusual smell and taste dysfunction arising from the SARS-CoV-2 pandemic. Over the next year, the GCCR used a highly collaborative model, along with contemporary Open Science practices, to produce multiple high impact publications on chemosensation and COVID19. This invited manuscript describes the founding of the GCCR, the tools and approaches it used, and a summary of findings to date. These findings are contextualized within a summary of some of the broader insights about chemosensation (smell, taste, and chemesthesis) and COVID19 gained over the last 18 months, including potential mechanisms of loss. Also, it includes a detailed discussion of some current Open Science approaches and practices used by the GCCR to increase transparency, rigor, and reproducibility.

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.

Olfactory and gustatory dysfunctions in SARS-CoV-2 infection: A systematic review

BACKGROUND

Among Coronavirus Disease 2019 (COVID-19) manifestations, Olfactory (OD) and Gustatory (GD) Dysfunctions (OGD) have drawn considerable attention, becoming a sort of hallmark of the disease. Many have speculated on the pathogenesis and clinical characteristics of these disturbances; however, no definite answers have been produced on the topic. With this systematic review, we aimed to collect all the available evidence regarding the prevalence of OGD, the timing of their onset and their resolution, their rate of recovery and their role as diagnostic and prognostic tools for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection.

METHODS

A systematic review comprising all the observational studies that reported the prevalence and/or the longitudinal trajectories of OGD in COVID-19 patients, as self-reported by patients or measured through objective psychophysical tests.

RESULTS

After the selection process, 155 studies were included, with a total of 70,920 patients and 105,291 not-infected individuals. Prevalence reports were extremely variable across studies, with wide ranges for OD (0%-98%) and GD (0-89%) prevalence. OGD occurred early during the disease course and only rarely preceded other symptoms; out of 30 studies with a follow-up time of at least 20 days, only in 5 studies OGD fully resolved in more than 90% of patients. OGD had low sensitivity and high specificity for SARS-CoV-2 infection; accuracy of OD and GD for infection identification was higher than 80% in 10 out of 33 studies and in 8 out of 22 studies considered, respectively. 28 out of 30 studies that studied the association between OGD and disease severity found how OGD were associated with lower rates of severe pneumonia, hospitalization and mortality.

CONCLUSIONS

OGD seem to be highly prevalent in SARS-CoV-2 infection. They occur early, concomitantly with other symptoms and often persist after recovery, in some cases for months; whether a full recovery eventually occurs in all cases is not clear yet. OGD are good predictors of SARS-CoV-2 infection and are associated with a milder disease course.

Sustained Chemosensory Dysfunction during the COVID-19 Pandemic

INTRODUCTION

Chemosensory dysfunction (CD) has proven valuable in prediction of COVID-19, as it is a frequent and specific symptom of the disease. The aim of this study was to investigate the duration of CD in patients with sudden subjective olfactory and/or gustatory loss during the SARS-CoV-2 pandemic. The secondary aim was to identify possible prognostic factors for the duration of CD.

METHODS

An online baseline questionnaire was designed to assess subjective CD. Three rounds of follow-up questionnaires were sent out to any participants with persistent CD in 6-week intervals, prospectively assessing subjective chemosensory function and extending the follow-up time of this cohort significantly.

RESULTS

In total, 467 participants completed the baseline questionnaire. The most significant improvement and recovery of chemosensory function was observed within the first month after the initial loss. Rates became stagnant after about 2 months, and only little improvement and recovery was seen after 2-4 months. After a mean follow-up of 95.9 days (olfactory dysfunction) and 94.0 days (gustatory dysfunction), 86.7% of participants reported gustatory improvement and 82.6% reported olfactory improvement, while 55.0% reported full gustatory recovery and 43.8% reported full olfactory recovery. Female gender was associated with better improvement of gustatory function. High subjective severity of chemosensory loss was associated with lower rates of olfactory and gustatory recovery as well as improvement of olfactory function. Young age was not associated with a better prognosis.

DISCUSSION/CONCLUSION

Rates of improvement and recovery of chemosensory function decreased after 2-4 months after initial chemosensory loss, possibly indicating that prolonged and perhaps permanent chemosensory loss may be a complication of SARS-CoV-2 infections. High subjective severity of CD may worsen the prognosis for improvement and recovery of chemosensory function.

Anosmia and dysgeusia in SARS-CoV-2 infection: incidence and effects on COVID-19 severity and mortality, and the possible pathobiology mechanisms - a systematic review and meta-analysis

Background: The present study aimed to determine the global prevalence of anosmia and dysgeusia in coronavirus disease 2019 (COVID-19) patients and to assess their association with severity and mortality of COVID-19. Moreover, this study aimed to discuss the possible pathobiological mechanisms of anosmia and dysgeusia in COVID-19. Methods: Available articles from PubMed, Scopus, Web of Science, and preprint databases (MedRxiv, BioRxiv, and Researchsquare) were searched on November 10th, 2020. Data on the characteristics of the study (anosmia, dysgeusia, and COVID-19) were extracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Newcastle-Ottawa scale was used to assess research quality. Moreover, the pooled prevalence of anosmia and dysgeusia were calculated, and the association between anosmia and dysgeusia in presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was assessed using the Z test. Results: Out of 32,142 COVID-19 patients from 107 studies, anosmia was reported in 12,038 patients with a prevalence of 38.2% (95% CI: 36.5%, 47.2%); whereas, dysgeusia was reported in 11,337 patients out of 30,901 COVID-19 patients from 101 studies, with prevalence of 36.6% (95% CI: 35.2%, 45.2%), worldwide. Furthermore, the prevalence of anosmia was 10.2-fold higher (OR: 10.21; 95% CI: 6.53, 15.96, p < 0.001) and that of dysgeusia was 8.6-fold higher (OR: 8.61; 95% CI: 5.26, 14.11, p < 0.001) in COVID-19 patients compared to those with other respiratory infections or COVID-19 like illness. To date, no study has assessed the association of anosmia and dysgeusia with severity and mortality of COVID-19. Conclusion: Anosmia and dysgeusia are prevalent in COVID-19 patients compared to those with the other non-COVID-19 respiratory infections. Several possible mechanisms have been hypothesized; however, future studies are warranted to elucidate the definitive mechanisms of anosmia and dysgeusia in COVID-19. Protocol registration: PROSPERO CRD42020223204.