Olfactory and gustatory dysfunction in COVID-19 patients: A meta-analysis study

Association between olfactory dysfunction and COVID-19 severity: A prospective study in a highly complex hospital in Peru

INTRODUCTION

Olfactory dysfunction has been included among the early symptoms of coronavirus disease (COVID-19). Evidence suggests that a relationship exists between the duration of olfaction disorders and the probability of developing severe COVID-19. Given the scope of the COVID-19 pandemic, this study aimed to determine the frequency of smell alteration and its association with the severity of COVID-19 in a referral hospital in Peru, which is one of the most affected countries in the Latin American region.

MATERIALS AND METHODS

This study was an observational, prospective cohort study that included patients with COVID-19 who were treated at the Hospital Nacional Edgardo Rebagliati Martins from August to November 2020. To assess the association, the chi-square test of independence or Fisher's exact test was performed. The outcome variable was COVID-19 severity, and the exposure variable was olfactory dysfunction. The first data collection was in the emergency department and the follow-up was via telephone.

RESULTS

A total of 179 patients were included. The mean age was 61.6 ± 15.5 years, and 129 patients (72.1%) were male. Olfactory dysfunction was observed in 43 patients (24%). An inverse association was found between age and olfactory dysfunction (P = .002). No significant association was found between COVID-19 severity level and olfactory alteration (P = .056). However, a direct association was found between COVID-19 severity and age (P = .003), cough (P < .001), and respiratory distress (P = .003).

CONCLUSION

This study did not find any association between the severity of COVID-19 and olfactory dysfunction. It showed a low incidence rate of smell alteration compared with studies from other regions. Moreover, smell alteration was associated with younger age.

Living and Coping with Olfactory and Taste Disorders: A Qualitative Study of People with Long-COVID-19

Taste and smell disorders are common symptoms of SARS-CoV-2 acute infection. In post-COVID-19 condition, symptoms can persist leading to disruption in patients' lives, to changes in their coping skills, and to the need to develop strategies for everyday life. This study aimed to describe the perspective of a group of patients with Long-COVID-19, a condition where loss of taste and/or smell was the most predominant symptom. A qualitative descriptive study was conducted. Participants who had suffered SARS-CoV-2 infection and had Long-COVID-19 loss of taste and/or smell were recruited. Purposive sampling was applied, and participants were recruited until data redundancy was reached. In-depth interviews were used for data collection and thematic analysis was applied. Twelve COVID-19 survivors (75% women) were recruited. The mean age of the participants was 55 years, and the mean duration of post-COVID-19 symptoms was 25 months. Three themes were identified: (a) Living with taste and smell disorders, describing the disorders they experience on a daily basis, how their life has changed and the accompanying emotions, (b) Changes and challenges resulting from the loss of taste and smell, changes in habits, self-care and risk in certain jobs or daily activities, (c) Coping with taste and smell disorders, describing the daily strategies used and the health care received. In conclusion, Long-COVID-19 taste and/or smell disorders limit daily life and involve changes in habits, meal preparation, and the ability to detect potentially dangerous situations.

Remote psychophysical testing of smell in patients with persistent olfactory dysfunction after COVID-19

Olfactory dysfunction associated with coronavirus 2 (SARS-CoV-2) infection is in most cases transient, recovering spontaneously within a few days. However, in some patients it persists for a long time, affects their everyday life and endangers their health. Hence, we focused on patients with persistent loss of smell. The aim of this study was to evaluate olfactory dysfunction using a standardized test. Due to the pandemic, olfactory testing was performed online. Smell tests (Odorized Markers Test, OMT) were sent home to the patients. Together with the smell self-testing, participants reported and assessed several parameters (age, sex, subjective assessment of smell and taste, nasal patency, etc.) in an online questionnaire. Based on the questionnaire outcomes, the results were sent to the patients along with a list of participating otolaryngologists who provided them with professional care. From March to June 2021, 1025 patients requested smell testing, of these, 824 met the inclusion criteria of this study. The duration of the olfactory dysfunction at the time of testing ranged from 1 month to 1 year. Using the OMT, impaired smell ability-anosmia or hyposmia-was confirmed in 82.6% of participants. A total of 17.4% of participants were determined to be normosmic however, more than 50% of them complained of parosmia and/or phantosmia. Our study demonstrates the relevance of psychophysical smell testing and its suitability for remote use during the pandemic. This study also revealed several correlations between prolonged olfactory dysfunction and the monitored parameters.

Lavender (Lavandula angustifolia) syrup as an adjunct to standard care in patients with mild to moderate COVID-19: An open-label, randomized, controlled clinical trial

Objective

ongoing COVID-19 pandemic has been associated with clinical signs characterized by fever, fatigue and cough. Our study aimed to assess the efficacy of a Persian medicine formulation, lavender syrup, as an add-on to standard care in patients with mild to moderate COVID-19.

Materials and Methods

In this clinical trial which was conducted in Gorgan (Iran), 84 male and female COVID-19 outpatients were randomly allocated to either lavender syrup receiving 9 ml/twice/day for 21 days with standard conventional care or control groups. The primary objectives were to assess the improvement of clinical symptoms, while the secondary objectives were treatment satisfaction and anxiety levels which were evaluated once a week for 3 weeks.

Results

Out of 84 participants, 81 were analyzed (41 in the add-on group). The comparison between groups for cough severity and anosmia showed a higher reduction in the lavender group. The effect size was 0.6 for cough relief. Other symptoms and the Hamilton total score decreased in both groups with no statistically significant differences between the groups. The lavender group showed greater patients' satisfaction score.

Conclusion

Adjunctive therapy with lavender syrup could reduce cough and improve the quality of life in patients with COVID-19 patients.

COVID-19 and coronary artery disease; A systematic review and meta-analysis

Background and aim

Patients with underlying cardiovascular disorders such as coronary artery disease (CAD) are more prone to severe forms and multiple complications of COVID-19. The present systematic review and meta-analysis aimed to investigate the impact of CAD on patients with COVID-19.

Methods

Main electronic databases, including Medline (via PubMed), EMBASE, and Web of Science, were carefully searched and reviewed for original research articles published between 2019 and 2021. One hundred nine studies that address CAD in patients with COVID-19 were selected and analyzed.

Results

Following search and screening processes, 109 relevant publications were selected for analysis. The meta-analysis of prevalence studies indicated that the frequency of CAD among patients with COVID-19 was reported in 10 countries with an overall frequency of 12.4% [(95% CI) 11.1-13.8] among 20079 COVID-19 patients. According to case reports/case series studies, 50.9% of COVID-19 patients suffered from CAD. Fever was the most common symptom in these patients (47%); 36.5% also had hypertension.

Conclusion

The results obtained during the present study show that the simultaneous presence of COVID-19 and CAD, especially in men and elderly patients, can increase the risks and complications of both diseases. Therefore, careful examination of the condition of this group of patients for timely diagnosis and treatment is strongly recommended.

Exploring Potential Biomarkers and Molecular Mechanisms of Ischemic Cardiomyopathy and COVID-19 Comorbidity Based on Bioinformatics and Systems Biology

Cardiovascular complications combined with COVID-19 (SARS-CoV-2) lead to a poor prognosis in patients. The common pathogenesis of ischemic cardiomyopathy (ICM) and COVID-19 is still unclear. Here, we explored potential molecular mechanisms and biomarkers for ICM and COVID-19. Common differentially expressed genes (DEGs) of ICM (GSE5406) and COVID-19 (GSE164805) were identified using GEO2R. We performed enrichment and protein–protein interaction analyses and screened key genes. To confirm the diagnostic performance for these hub genes, we used external datasets (GSE116250 and GSE211979) and plotted ROC curves. Transcription factor and microRNA regulatory networks were constructed for the validated hub genes. Finally, drug prediction and molecular docking validation were performed using cMAP. We identified 81 common DEGs, many of which were enriched in terms of their relation to angiogenesis. Three DEGs were identified as key hub genes (HSP90AA1, HSPA9, and SRSF1) in the protein–protein interaction analysis. These hub genes had high diagnostic performance in the four datasets (AUC > 0.7). Mir-16-5p and KLF9 transcription factor co-regulated these hub genes. The drugs vindesine and ON-01910 showed good binding performance to the hub genes. We identified HSP90AA1, HSPA9, and SRSF1 as markers for the co-pathogenesis of ICM and COVID-19, and showed that co-pathogenesis of ICM and COVID-19 may be related to angiogenesis. Vindesine and ON-01910 were predicted as potential therapeutic agents. Our findings will contribute to a deeper understanding of the comorbidity of ICM with COVID-19.

Temporal pattern of humoral immune response in mild cases of COVID-19

BACKGROUND

Understanding the humoral response pattern of coronavirus disease 2019 (COVID-19) is one of the essential factors to better characterize the immune memory of patients, which allows understanding the temporality of reinfection, provides answers about the efficacy and durability of protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and consequently helps in global public health and vaccination strategy. Among the patients who became infected with SARS-CoV-2, the majority who did not progress to death were those who developed the mild COVID-19, so understanding the pattern and temporality of the antibody response of these patients is certainly relevant.

AIM

To investigate the temporal pattern of humoral response of specific immunoglobulin G (IgG) in mild cases of COVID-19.

METHODS

Blood samples from 191 COVID-19 real-time reverse transcriptase-polymerase chain reaction (RT-qPCR)-positive volunteers from the municipality of Toledo/ Paraná/Brazil, underwent two distinct serological tests, enzyme-linked immunosorbent assay, and detection of anti-nucleocapsid IgG. Blood samples and clinicoepidemiological data of the volunteers were collected between November 2020 and February 2021. All assays were performed in duplicate and the manufacturers' recommendations were strictly followed. The data were statistically analyzed using multiple logistic regression; the variables were selected by applying the P < 0.05 criterion.

RESULTS

Serological tests to detect specific IgG were performed on serum samples from volunteers who were diagnosed as being positive by RT-qPCR for COVID-19 or had disease onset in the time interval from less than 1 mo to 7 mo. The time periods when the highest number of participants with detectable IgG was observed were 1, 2 and 3 mo. It was observed that 9.42% of participants no longer had detectable IgG antibodies 1 mo only after being infected with SARS-CoV-2 and 1.57% were also IgG negative at less than 1 mo. At 5 mo, 3.14% of volunteers were IgG negative, and at 6 or 7 mo, 1 volunteer (0.52%) had no detectable IgG. During the period between diagnosis by RT-qPCR/symptoms onset and the date of collection for the study, no statistical significance was observed for any association analyzed. Moreover, considering the age category between 31 and 59 years as the exposed group, the P value was 0.11 for the category 31 to 59 years and 0.32 for the category 60 years or older, showing that in both age categories there was no association between the pair of variables analyzed. Regarding chronic disease, the exposure group consisted of the participants without any comorbidity, so the P value of 0.07 for the category of those with at least one chronic disease showed no association between the two variables.

CONCLUSION

A temporal pattern of IgG response was not observed, but it is suggested that immunological memory is weak and there is no association between IgG production and age or chronic disease in mild COVID-19.

Chemosensory Ability and Sensitivity in Health and Disease: Epigenetic Regulation and COVID-19

Throughout the animal kingdom, our two chemical senses, olfaction and gustation, are defined by two primary factors: genomic architecture of the organisms and their living environment. During the past three years of the global COVID-19 pandemic, these two sensory modalities have drawn much attention at the basic science and clinical levels because of the strong association of olfactory and gustatory dysfunction with viral infection. Loss of our sense of smell alone, or together with a loss of taste, has emerged as a reliable indicator of COVID-19 infection. Previously, similar dysfunctions have been detected in a large cohort of patients with chronic conditions. The research focus remains on understanding the persistence of olfactory and gustatory disturbances in the post-infection phase, especially in cases with long-term effect of infection (long COVID). Also, both sensory modalities show consistent age-related decline in studies aimed to understand the pathology of neurodegenerative conditions. Some studies using classical model organisms show an impact on neural structure and behavior in offspring as an outcome of parental olfactory experience. The methylation status of specific odorant receptors, activated in parents, is passed on to the offspring. Furthermore, experimental evidence indicates an inverse correlation of gustatory and olfactory abilities with obesity. Such diverse lines of evidence emerging from basic and clinical research studies indicate a complex interplay of genetic factors, evolutionary forces, and epigenetic alterations. Environmental factors that regulate gustation and olfaction could induce epigenetic modulation. However, in turn, such modulation leads to variable effects depending on genetic makeup and physiological status. Therefore, a layered regulatory hierarchy remains active and is passed on to multiple generations. In the present review, we attempt to understand the experimental evidence that indicates variable regulatory mechanisms through multilayered and cross-reacting pathways. Our analytical approach will add to enhancement of prevailing therapeutic interventions and bring to the forefront the significance of chemosensory modalities for the evaluation and maintenance of long-term health.

Olfactory and Gustatory Dysfunction in COVID-19: A Global Bibliometric and Visualized Analysis

OBJECTIVES

Coronavirus illness (COVID-19) has been found to alter infected people's sense of smell and taste. However, the pathobiology of this virus is not yet known. Therefore, it is critical to investigate the influence of COVID-19 infection on olfactory and gustatory processes. Therefore, we use bibliometric analysis on COVID-19 and olfactory and/or gustatory dysfunction publications to provide studies perspective.

METHODS

A bibliometric literature search was performed in the Scopus database. The number and type of publications, countries for publications, institutional sources for publications, journals for publications, citation patterns, and funding agencies were analyzed using Microsoft Excel or VOSviewer. In addition, the VOSviewer 1.6.17 software was used to analyze and visualize hotspots and collaboration patterns between countries.

RESULTS

Scopus has published 187 088 documents for COVID-19 in all study fields at the time of data collection (July 26, 2021). A total of 1740 documents related to olfactory and/or gustatory dysfunction were recovered. The countries most relevant by the number of publications were the United States (n = 362, 20.80%), Italy (n = 255, 14.66%), and the United Kingdom (n = 173, 9.94%). By analyzing the terms in the titles and abstracts, we identified 2 clusters related to olfactory and/or gustatory dysfunction research, which are "diagnosis and test methods" and "prognosis and complications of the disease."

CONCLUSIONS

This is the first bibliometric analysis of publications related to COVID-19 and olfactory and/or gustatory dysfunction. This study provides academics and researchers with useful information on the publishing patterns of the most influential publications on COVID-19 and olfactory and/or gustatory dysfunction. Olfactory and/or gustatory dysfunction as indices of suspicion for the empirical diagnosis of coronavirus infection is a new hotspot in this field.

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.

Post Viral Olfactory Dysfunction After SARS-CoV-2 Infection: Anticipated Post-pandemic Clinical Challenge

Persistent olfactory dysfunction (OD) is the second most common symptom of post coronavirus disease-19 (COVID-19) now being termed long-COVID. Its prevalence after recovery from COVID-19 is estimated to be 12% after nearly 6 months of follow-up. It thus becomes imperative for the treating clinicians to update themselves with the pathophysiology of this post COVID disability as well as the tools for diagnosis and the available treatment options. A systematic literature search was performed as per PRISMA guidelines in MEDLINE, Cochrane Library, LILACS, Google Scholar, ClinicalTrials.gov, and medRxiv databases. The keywords used were covid-19, Olfactory Disorders, Smell, Anosmia, PVOD, Post Viral Olfactory Disorders, post-covid and post haul. All articles were studied for definition, mechanism, diagnostic tests and treatment options for post COVID OD. 33 published articles and 8 ongoing trials were found relevant and included after full-text review. SARS-CoV-2 can cause conductive, neural and central OD. Olfactory evaluation can be done both subjectively (visual analogue scale) and objectively (Sniffin' sticks, Sinonasal Outcome Test, University of Pennsylvania Smell Identification Test and modified Davidson's alcohol sniff test). They can be used to detect and follow-up patients. Despite several on-going clinical trials, the most reliable and advisable treatment option available till date is olfactory training.

Factors Associated with Delayed Diagnosis among Patients with COVID-19 in Okinawa, Japan

The delayed presentation and diagnosis of COVID-19 can contribute to spread of the disease to others but can also cause severe conditions. This study examined factors associated with delayed diagnosis among patients with COVID-19 in Okinawa, Japan. We used the data from 7125 reported cases of people living in Okinawa prefecture with symptom onset between September 2020 and March 2021. The outcome variable was the number of days from symptom onset to diagnosis. The predictor variables included age, sex, occupation, residential area, presumed infection route, and the day of the week. Cox regression analysis was used to compare the outcome between categories for each predictor variable. The median number of days from onset to diagnosis was 3 days, with an interquartile range of 1 to 5 days. Significantly more time from onset to diagnosis was observed in patients in their 60s vs. those in their 20s (hazard ratio: 0.88; 95% confidence interval: 0.81-0.96); hospitality workers were compared to office workers (0.90; 0.83-0.97), patients with unknown infection routes to those with known infection routes (0.77; 0.70-0.84), and those with symptom onset on Sundays/national holidays to those with symptom onset on weekdays (0.90; 0.85-0.96).

Hearing loss and the COVID-19 pandemic

Objective

Hearing loss is an important public health problem. Its causes vary, including infections, noise, and aging. The first wave of the COVID-19 pandemic occurred in April 2020 in Japan. During the pandemic, people were urged to stay at home and drastically changed their lifestyles. This study aimed to examine hearing loss before and during the pandemic. The prevalence during the pandemic after April 2020 was compared for the period in 2019. Study subjects were those who received health checkups in both periods. Hearing loss was defined as a hearing threshold of > 30 dB at 1 kHz and > 40 dB at 4 kHz in either ear using pure-tone audiometry.

Results

A total of 2367 persons presented in both 2019 and 2020. The overall rates of hearing loss were 9.5% and 13.2% before and after the pandemic, respectively. After controlling for age, sex, current smoking, regular exercise and alcohol consumption, the rate of hearing loss showed a significant increase in 2020 (p =  < 0.0001). With age stratification, an increase was observed in the participants aged < 40 years (1.3% vs. 3.1%, p < 0.001) and 40–59 years (7.2% vs. 12.6%, p < 0.001). Further studies are needed to confirm the impact of the COVID-19 pandemic on hearing loss.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06120-1.

Gustatory and Saliva Secretory Dysfunctions in COVID-19 Patients with Zinc Deficiency

Given the ever-progressing studies on coronavirus disease 2019 (COVID-19), it is critical to update our knowledge about COVID-19 symptomatology and pathophysiology. In the present narrative review, oral symptoms were overviewed using the latest data and their pathogenesis was hypothetically speculated. PubMed, LitCovid, ProQuest, and Google Scholar were searched for relevant studies from 1 April 2021 with a cutoff date of 31 January 2022. The literature search indicated that gustatory dysfunction and saliva secretory dysfunction are prevalent in COVID-19 patients and both dysfunctions persist after recovery from the disease, suggesting the pathogenic mechanism common to these cooccurring symptoms. COVID-19 patients are characterized by hypozincemia, in which zinc is possibly redistributed from blood to the liver at the expense of zinc in other tissues. If COVID-19 induces intracellular zinc deficiency, the activity of zinc-metalloenzyme carbonic anhydrase localized in taste buds and salivary glands may be influenced to adversely affect gustatory and saliva secretory functions. Zinc-binding metallothioneins and zinc transporters, which cooperatively control cellular zinc homeostasis, are expressed in oral tissues participating in taste and saliva secretion. Their expression dysregulation associated with COVID-19-induced zinc deficiency may have some effect on oral functions. Zinc supplementation is expected to improve oral symptoms in COVID-19 patients.

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.

Subjective Mouthfeel and Temperature Alterations in COVID-19 Patients Six to Ten Months After Diagnosis

Introduction

The characteristics and impact of mouthfeel, temperature, smell, and taste alterations in patients with COVID-19 at a long term are yet not well known. In this study, these characteristics and their impact on daily life and quality of life (QoL) were assessed, six to ten months after infection, in patients with COVID-19 searching for peer support on Facebook.

Methods

Between December 2020 and January 2021, members of two COVID-19 Facebook groups were invited to complete a questionnaire. Participants were asked to report their perception of mouthfeel, temperature, smell, and taste alterations and their impact.

Results

The questionnaire was completed by 157/216 respondents (73%), with 92% being women. Alterations in mouthfeel, temperature, smell, and taste were reported by respectively 66, 40, 148, and 133 participants. The most frequently reported mouthfeel alterations were "a different feeling" and "dry mouth" in 38 and 30 participants, respectively. Preferences for food temperature were equally changed to "freezing", "cool", "room temperature", "a bit warmer", and "warmer". An impact on daily life and QoL was reported by most patients with alterations in mouthfeel (91% and 79%), temperature (78% and 60%), smell (98% and 93%), and taste (93% and 88%), respectively.

Conclusions

Patients with COVID-19 searching for peer support on Facebook experienced, next to smell and taste alterations, mouthfeel and temperature disturbances, six to ten months after infection. These alterations have an impact on daily life and QoL.

Implications

Health professionals should, next to smell and taste alterations, be aware of mouthfeel and temperature alterations in patients with COVID-19.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12078-022-09304-y.

COVID-19, anosmia, and ageusia in atopic children

More than a year and a half after the beginning of the coronavirus disease 2019 (COVID-19) pandemic, symptoms, such as loss of smell and taste (anosmia and ageusia, respectively), remain difficult to characterize and quantify, especially in children, since no validated tests to assess these disorders are available. However, these symptoms can also be seen in children, although less frequently than observed in the adult population. In this article, we present the results of a national survey that collected the responses of 267 Italian pediatricians on the presence of anosmia and ageusia in children affected by COVID-19. These data were then compared with existing literature.

Possible Role of Endocannabinoids in Olfactory and Taste Dysfunctions in COVID-19 Patients and Volumetric Changes in the Brain

Introduction

COVID-19 infection develops neurologic symptoms such as smell and taste loss. We aimed to determine the volumetric changes in the brain and correlation of possible related biochemical parameters and endocannabinoid levels after COVID-19 recovery.

Methods

Brain magnetic resonance images of recovered COVID-19 patients and healthy volunteers, whose olfactory and gustatory scores were obtained through a questionnaire, were taken, and the volumes of the brain regions associated with taste and smell were measured by automatic and semiautomatic methods. Endocannabinoids (EC), which are critical in the olfactory system, and vitamin B12, zinc, iron, ferritin, thyroid-stimulating hormone (TSH), and thyroxine (T4) levels, which are reported to have possible roles in olfactory disorders, were measured in peripheral blood.

Results

Taste and smell disorder scores and EC levels were found to be higher in recovered COVID-19 patients compared to controls. EC levels were negatively correlated with bilateral entorhinal cortex (ENT) volumes in the COVID-19 group. Subgenual anterior cingulate cortex volumes showed correlations with gustatory complaints and ferritin in recovered COVID-19 patients.

Conclusions

The critical finding of our study is the high EC levels and negative correlation between EC levels and left ENT volumes in recovered COVID-19 patients.

Implications

It is possible that ECs are potential neuromodulators in many conditions leading to olfactory disorders, including COVID-19.

The COVOSMIA-19 trial: Preliminary application of the Singapore smell and taste test to objectively measure smell and taste function with COVID-19

Sudden loss of smell and/or taste has been identified as an early symptom of SARS-CoV-2 2019 (COVID-19) infection, and presents an effective target for prompt self-isolation and reducing community spread. The current study sought to develop and test a novel, rapid, self-administered test to objectively measure smell and taste losses associated with COVID-19, and administered self-report questionnaires to characterise symptoms associated with COVID-19 in Singapore. Participants (N = 99) completed questionnaires to record recent changes in smell and taste ability. This was followed by the ‘Singapore Smell and Taste Test’ (SSTT), a personal, objective testing kit for daily self-assessment of smell and taste function at their place of residence. Seventy-two recruited participants were confirmed as COVID-19 positive at baseline, of which 58 completed the SSTT at home. Of these, 36.2% had objectively measured smell and/or taste loss. The SSTT measures of smell and taste function were positively associated with participants’ self-reported smell and taste acuity, and rated smell intensity of 6 common household items. This study presents the first application of the SSTT as a rapid, cost-effective, objective tool to self-monitor smell and taste function in a residential setting, and ensures comparability across individuals through the use of standardised stimuli. The SSTT has potential for future application in populations with limited access to formal COVID-19 testing as a self-administered objective method to monitor sudden changes in smell and taste, and to prompt early self-isolation, in order to reduce community transmission of COVID-19.

Could smell and taste dysfunction in COVID-19 patients be a sign of the clinical course of the disease?

Background

It could be of great benefit to determine smell and taste dysfunction in COVID-19 patients and to investigate the relationship between these symptoms and clinical characteristics as the determination of points requiring attention during the clinical course of the disease.

Method

Evaluations of patients diagnosed with COVID-19 were made using a questionnaire method. Those with smell and taste dysfunction completed a visual analog scale (VAS) to determine severity. The patients were evaluated at the end of 1 and 2 months.

Results

Evaluation was made of a total of 105 patients with a mean age of 55.9±17.6 years. Smell and taste dysfunction was present in 56 (53.3%) patients with a mean age of 48.7±17.6 years and the 49 (46.7%) patients with no smell and taste dysfunction had a mean age of 64±13.6 years. It was determined that as age increased, the complaints of smell and taste dysfunction decreased. Full recovery was determined in 31 (55%) patients after 1 month, and in 16 (28%) patients, smell and taste dysfunction continued at the end of the second month. The symptoms of smell and taste dysfunction were determined to last longer in patients with no comorbidities, no symptoms of fever or shortness of breath, and those treated as outpatients (p=0.043, p=0.031, p=0.034, p=0.028, respectively). In the older age patient group, the VAS scores were observed to be higher and the time to recovery was shorter (p=0.007, p=0.018, respectively).

Conclusion

Smell and taste dysfunction in COVID-19 patients is seen more as age decreases and recovery takes longer. Smell and taste dysfunction is seen more in patients with symptoms of cough, nasal obstruction, and headache and lasts longer in patients without symptoms of fever and shortness of breath, with no comorbidities and in those treated as outpatients.

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.

Neurological manifestations of COVID-19 infection: an umbrella review

BACKGROUND

Neurological involvements of COVID-19 are one of the most reported manifestations of this infection. This study aims to systematically review the previous systematic reviews which addressed the neurological manifestations of the COVID-19 infection.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, a comprehensive search was conducted in PubMed, Embase, Scopus, Web of Science databases and Google Scholar from December 2019 to December 2020. Articles were critically screened by two independent reviewers and if met the inclusion criteria, entered the study. Assessment of methodological quality was conducted by Assessment of Multiple Systematic Reviews-2 (AMSTAR-2) tool. Statistical analysis was not applicable. From a total of 1302 studies, 308 studies were removed due to their irrelevant title and abstract. After screening the full texts, a total of 66 found to be eligible. Twenty-one studies reported general manifestations of the COVID-19, 13 studies reported cerebrovascular events, 19 olfactory and oral dysfunctions, 5 systematic reviews on Guillen-Barré syndrome (GBS) and 8 articles on the sporadic manifestations like ocular signs and symptoms. The majority of the studies were classified as critically low or low in terms of quality.

CONCLUSION

Despite great heterogeneity in the current literature, neurological involvements are an important extra-pulmonary aspect of the COVID-19; most commonly in the form of general manifestations like headache and olfactory disturbances. Long-term effects of this virus on the nervous system must be a research priority for future references.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s41983-021-00366-5.

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.

Is loss of smell an early predictor of COVID-19 severity: a systematic review and meta-analysis

Anecdotal evidence suggests that the severity of coronavirus disease of 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is likely to be distinguished by variations in loss of smell (LOS). Thus, we conducted a meta-analysis of 45 articles that include a total of 42,120 COVID-19 patients from 17 different countries to demonstrate that severely ill or hospitalized COVID-19 patients have a lesser chance of experiencing LOS than non-severely ill or non-hospitalized COVID-19 patients (odds ratio = 0.527 [95% CI 0.373–0.744; p < 0.001] and 0.283 [95% CI 0.173–0.462; p < 0.001], respectively). We also proposed a possible mechanism underlying the association of COVID-19 severity with anosmia, which may explain why patients without sense of smell develop severe COVID-19. Variations in LOS according to the severity of COVID-19 is a global phenomenon, with few exceptions. Since severely ill patients have a lower rate of anosmia, patients without anosmia should be monitored more closely in the early stages of COVID-19, for early diagnosis of severity of illness. An understanding of how the severity of COVID-19 infection and LOS are associated has profound implications for the clinical management and mitigation strategies for the disease.

Risk Factors and Clinical Phenotypes Associated with Severity in Patients with COVID-19 in Northeast Mexico

Objective: The aim of this study is to describe the main clinical phenotypes, laboratory findings, and severity of coronavirus disease 2019 (COVID-19) in patients hospitalized at the High Specialty Medical Unit # 71 of the Mexican Social Security Institute. Methods: Prospective observational cohort study with a total of 105 patients hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection at the High Specialty Medical Unit # 71 (Torreón, Coahuila, Mexico), from May 15th to August 15th, 2020. The cases were confirmed to be COVID-19 positive through an RT-qPCR test. Clinical phenotypes and laboratory tests were evaluated to determine the degree of severity of the disease and the most frequent comorbidities. Results: The clinical characteristics of a total of 105 hospitalized patients (47 females and 58 males; median age being 52 years) with confirmed COVID-19 diagnoses were studied. The severity of the disease was classified as moderate grade (62.7%), severe grade (21.5%), and critical grade (15.6%). Among the most frequent underlying pathologies coexisted overweight (n = 75, 78.12%), obesity (n = 21, 21.87%), diabetes (n = 10, 9.52%), and hypertension (n = 6, 5.71%), some of these patients present more than one pathology. This association was found with diabetes (odds ratio [OR]: 1.42; 95% confidence interval [CI]: 1.23-1.97; p = 0.021) and high levels of D-dimer (OR: 1.01; 95% CI: 1.00-1.08; p = 0.001). Conclusion: In this retrospective cohort study of patients with COVID-19 from a specialty hospital in the northeast region of Mexico, it was observed that clinical phenotypes and D-dimer elevation were compatible with an inflammatory state by degree of severity; it was found that the hospitalized patients with underlying chronic medical conditions such as diabetes and elevated D-dimer levels were significantly associated with increased mortality from COVID-19. Age and sex (males) were two factors highly associated with mortality.

COVID-19 and Cardiomyopathy: A Systematic Review

Background: Cardiomyopathies (CMPs) due to myocytes involvement are among the leading causes of sudden adolescent death and heart failure. During the COVID-19 pandemic, there are limited data available on cardiac complications in patients with COVID-19, leading to severe outcomes.

Methods: We conducted a systematic search in Pubmed/Medline, Web of Science, and Embase databases up to August 2020, for all relevant studies about COVID-19 and CMPs.

Results: A total of 29 articles with a total number of 1460 patients were included. Hypertension, diabetes, obesity, hyperlipidemia, and ischemic heart disease were the most reported comorbidities among patients with COVID-19 and cardiomyopathy. In the laboratory findings, 21.47% of patients had increased levels of troponin. Raised D-dimer levels were also reported in all of the patients. Echocardiographic results revealed mild, moderate, and severe Left Ventricular (LV) dysfunction present in 17.13, 11.87, and 10% of patients, respectively.

Conclusions: Cardiac injury and CMPs were common conditions in patients with COVID-19. Therefore, it is suggested that cardiac damage be considered in managing patients with COVID-19.

COVID-19 survivorship: How otolaryngologist-head and neck surgeons can restore quality of life after critical illness

Mortality from COVID-19 has obscured a subtler crisis – the swelling ranks of COVID-19 survivors. After critical illness, patients often suffer post-intensive care syndrome (PICS), which encompasses physical, cognitive, and/or mental health impairments that are often long-lasting barriers to resuming a meaningful life. Some deficits after COVID-19 critical illness will require otolaryngologic expertise for years after hospital discharge. There are roles for all subspecialties in preventing, diagnosing, or treating sequelae of COVID-19. Otolaryngologist leadership in multidisciplinary efforts ensures coordinated care. Timely tracheostomy, when indicated, may shorten the course of intensive care unit stay and thereby potentially reduce the impairments associated with PICS. Otolaryngologists can provide expertise in olfactory disorders; thrombotic sequelae of hearing loss and vertigo; and laryngotracheal injuries that impair speech, voice, swallowing, communication, and breathing. In the aftermath of severe COVID-19, otolaryngologists are poised to lead efforts in early identification and intervention for impairments affecting patients' quality of life.

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.

Systemic corticosteroids in coronavirus disease 2019 (COVID-19)-related smell dysfunction: an international view

The frequent association between coronavirus disease 2019 (COVID‐19) and olfactory dysfunction is creating an unprecedented demand for a treatment of the olfactory loss. Systemic corticosteroids have been considered as a therapeutic option. However, based on current literature, we call for caution using these treatments in early COVID‐19–related olfactory dysfunction because: (1) evidence supporting their usefulness is weak; (2) the rate of spontaneous recovery of COVID‐19–related olfactory dysfunction is high; and (3) corticosteroids have well‐known potential adverse effects. We encourage randomized placebo‐controlled trials investigating the efficacy of systemic steroids in this indication and strongly emphasize to initially consider smell training, which is supported by a robust evidence base and has no known side effects.

Respiratory and Psychophysical Sequelae Among Patients With COVID-19 Four Months After Hospital Discharge

IMPORTANCE

Although plenty of data exist regarding clinical manifestations, course, case fatality rate, and risk factors associated with mortality in severe coronavirus disease 2019 (COVID-19), long-term respiratory and functional sequelae in survivors of COVID-19 are unknown.

OBJECTIVE

To evaluate the prevalence of lung function anomalies, exercise function impairment, and psychological sequelae among patients hospitalized for COVID-19, 4 months after discharge.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study at an academic hospital in Northern Italy was conducted among a consecutive series of patients aged 18 years and older (or their caregivers) who had received a confirmed diagnosis of severe acute respiratory coronavirus 2 (SARS-CoV-2) infection severe enough to require hospital admission from March 1 to June 29, 2020. SARS-CoV-2 infection was confirmed via reverse transcription-polymerase chain reaction testing, bronchial swab, serological testing, or suggestive computed tomography results.

EXPOSURE

Severe COVID-19 requiring hospitalization.

MAIN OUTCOMES AND MEASURES

The primary outcome of the study was to describe the proportion of patients with a diffusing lung capacity for carbon monoxide (Dlco) less than 80% of expected value. Secondary outcomes included proportion of patients with severe lung function impairment (defined as Dlco <60% expected value); proportion of patients with posttraumatic stress symptoms (measured using the Impact of Event Scale-Revised total score); proportion of patients with functional impairment (assessed using the Short Physical Performance Battery [SPPB] score and 2-minute walking test); and identification of factors associated with Dlco reduction and psychological or functional sequelae.

RESULTS

Among 767 patients hospitalized for severe COVID-19, 494 (64.4%) refused to participate, and 35 (4.6%) died during follow-up. A total of 238 patients (31.0%) (median [interquartile range] age, 61 [50-71] years; 142 [59.7%] men; median [interquartile range] comorbidities, 2 [1-3]) consented to participate to the study. Of these, 219 patients were able to complete both pulmonary function tests and Dlco measurement. Dlco was reduced to less than 80% of the estimated value in 113 patients (51.6%) and less than 60% in 34 patients (15.5%). The SPPB score was suggested limited mobility (score <11) in 53 patients (22.3%). Patients with SPPB scores within reference range underwent a 2-minute walk test, which was outside reference ranges of expected performance for age and sex in 75 patients (40.5%); thus, a total of 128 patients (53.8%) had functional impairment. Posttraumatic stress symptoms were reported in a total of 41 patients (17.2%).

CONCLUSIONS AND RELEVANCE

These findings suggest that at 4 months after discharge, respiratory, physical, and psychological sequelae were common among patients who had been hospitalized for COVID-19.

Chemosensory Dysfunctions Induced by COVID-19 Can Persist up to 7 Months: A Study of Over 700 Healthcare Workers

Several studies have revealed either self-reported chemosensory alterations in large groups or objective quantified chemosensory impairments in smaller populations of patients diagnosed with COVID-19. However, due to the great variability in published results regarding COVID-19-induced chemosensory impairments and their follow-up, prognosis for chemosensory functions in patients with such complaints remains unclear. Our objective is to describe the various chemosensory alterations associated with COVID-19 and their prevalence and evolution after infection. A cross-sectional study of 704 healthcare workers with a RT–PCR-confirmed SARS-CoV-2 infection between 2020 February 28 and 2020 June 14 was conducted 3–7 months after onset of symptoms. Data were collected with an online questionnaire. Outcomes included differences in reported chemosensory self-assessment of olfactory, gustatory, and trigeminal functions across time points and Chemosensory Perception Test scores from an easy-to-use at-home self-administered chemosensory test. Among the 704 participants, 593 (84.2%) were women, the mean (SD) age was 42 (12) years, and the questionnaire was answered on average 4.8 (0.8) months after COVID-19. During COVID-19, a decrease in olfactory, gustatory, and trigeminal sensitivities was reported by 81.3%, 81.5%, and 48.0%, respectively. Three to 7 months later, reduced sensitivity was still reported by 52.0%, 41.9%, and 23.3%, respectively. Chemosensory Perception Test scores indicate that 19.5% of participants had objective olfactory impairment. These data suggest a significant proportion of COVID-19 cases have persistent chemosensory impairments at 3–7 months after their infection, but the majority of those who had completely lost their olfactory, gustatory, and trigeminal sensitivities have improved.

Taste and Smell Impairment in Critically Ill Patients With COVID-19: An Intensive Care Unit Study

OBJECTIVE

To determine taste and smell impairment rates in patients with coronavirus disease 2019 (COVID-19) who were hospitalized in the intensive care unit (ICU).

METHODS

Between March 2020 and May 2020, patients with COVID-19 hospitalized in the ICU were enrolled in this study. Upon discharge, patients were telephoned and asked to complete a survey related to taste and smell impairment. Characteristics were compared between patients with and without taste and/or smell impairment.

RESULTS

Fifty-two patients were enrolled (mean age, 61.32 ± 12.53 years; mean ICU stay, 10.19 ± 10.24 days). Age, sex, type/number of comorbid diseases, most ICU support modalities, and ICU stay duration did not significantly differ between groups. Patients in group B required more high-flow nasal oxygen therapy than patients in group A (P = .010). In total, 22 (42.3%) of 52 patients experienced taste and/or smell impairment. Three patients experienced isolated smell impairment and one patient experienced isolated taste impairment. Among the 21 patients who experienced smell impairment, 18 (85.78%) experienced hyposmia (mean visual analog scale [VAS] score: 6.33 ± 0.97), while 3 (14.28%) experienced anosmia. Among the 19 patients who experienced taste impairment, 16 (84.22%) experienced hypogeusia (mean VAS score: 6.43 ± 1.03) and 3 (15.78%) experienced ageuisa. Among 22 patients who experienced taste and/or smell impairment, 15 (68.18%) patients (n = 15/22) experienced smell and/or taste impairment before the ICU stay, while 7 (31.82%) patients (n = 7/22) experienced impairment during the ICU stay. Overall, 28.84% (n = 15/52) of the patients experienced taste and/or smell impairment before the ICU stay.

CONCLUSIONS

Patients who were hospitalized in the ICU experienced lower rates of taste and/or smell impairment. Some patients experienced taste and/or smell impairment during the ICU stay.

Attributes of dysgeusia and anosmia of coronavirus disease 2019 (COVID-19) in hospitalized patients

OBJECTIVES

While chemosensory dysfunctions, dysgeusia and anosmia/hyposmia, are recognized as distinctive symptoms of COVID-19, their temporality of presentation and association with the patient age, gender, disease severity, and comorbidities has been sparsely studied. Hence, we evaluated the latter associations of chemosensory dysfunction, in hospitalized COVID-19 patients in the United Arab Emirates (UAE).

MATERIALS AND METHODS

Information on chemosensory dysfunction and history of chronic systemic comorbidities, if any, was obtained from 149 COVID-19 patients in an infectious disease hospital in UAE, using their medical records, as well as from a face-to-face questionnaire survey. Additionally, a modified SNOT-22 questionnaire that measures disease-specific quality of life in patients with upper respiratory tract affections was also administered.

RESULTS

Chemosensory dysfunction was reported by 94.6% of the cohort, and anosmia with dysgeusia was significantly more in males than females with severe COVID-19. Males with moderate COVID-19 and systemic comorbidities were more likely to present with chemosensory dysfunction in comparison with females. SNOT-22 questionnaire revealed that nasal blockage and runny nose were more prevalent in mild/moderate, than in the severe, state of COVID-19.

CONCLUSION

Our data confirm the commonality of chemosensory dysfunction during COVID-19 progression, and the significantly more pronounced combined dysfunction in males with severe COVID-19, and comorbidities.