Prevalence of Chemosensory Dysfunction in COVID-19 Patients: A Systematic Review and Meta-analysis Reveals Significant Ethnic Differences

An A-E assessment of post-ICU COVID-19 recovery

The COVID-19 global pandemic has placed unprecedented strain on healthcare and critical care services around the world. Whilst most resources have focused on the acute phase of the disease, there is likely to be an untold burden of patients chronically affected.A wide range of sequelae contribute to post intensive care syndrome (PICS); from our current knowledge of COVID-19, a few of these have the potential to be more prevalent following critical care admission. Follow-up assessment, diagnosis and treatment in an increasingly virtual setting will provide challenges but also opportunities to develop these services. Here, we propose an A to E approach to consider the potential long-term effects of COVID-19 following critical care admission.Anxiety and other mental health diagnosesBreathlessnessCentral nervous system impairmentDietary insufficiency and malnutritionEmbolic eventsDeveloping strategies to mitigate these during admission and providing follow-up, assessment and treatment of persistent multiple organ dysfunction will be essential to improve morbidity, mortality and patient quality of life.

Comparative Study of Chemosensory Dysfunction in COVID-19 in 2 Geographically Distinct Regions

OBJECTIVE

To directly compare the prevalence of chemosensory dysfunction (smell and taste) in geographically distinct regions with the same questionnaires.

METHODS

A cross-sectional study was performed to evaluate the self-reported symptoms among adults (older than 18 years) who underwent COVID-19 testing at an ambulatory assessment center in Canada and at a hospital in Israel between March 16, 2020, and August 19, 2020. The primary outcome was the prevalence of self-reported chemosensory dysfunction (anosmia/hypomsia and dysgeusia/ageusia). Subgroup analysis was performed to evaluate the prevalence of chemosensory deficits among the outpatients.

RESULTS

We identified a total of 350 COVID-19-positive patients (138 Canadians and 212 Israelis). The overall prevalence of chemosensory dysfunction was 47.1%. There was a higher proportion of chemosensory deficits among Canadians compared to Israelis (66.7% vs 34.4%, P < .01). A subgroup analysis for outpatients (never hospitalized) still identified a higher prevalence of chemosensory dysfunction among Canadians compared to Israelis (68.2% vs 36.1%, P < 0.01). A majority of patients recovered their sense of smell after 4 weeks of symptom onset.

CONCLUSION

Although the prevalence of chemosensory deficit in COVID-19 was found to be similar to previously published reports, the prevalence can vary significantly across different geographical regions. Therefore, it is important to obtain regionally specific data so that the symptom of anosmia/dysgeusia can be used as a guide for screening for the clinical diagnosis of COVID-19.

Oral Symptoms Associated with COVID-19 and Their Pathogenic Mechanisms: A Literature Review

Since the worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, management of coronavirus disease 2019 (COVID-19) has been challenging for healthcare providers. The oral cavity is referred to as a target of SARS-CoV-2. The aim of this study was to review oral symptoms specific to COVID-19 patients from the point of view of symptom prevalence and pathogenesis and to speculate the pathogenic mechanisms underlying them. Scientific articles were retrieved by searching PubMed/MEDLINE, Google Scholar, medRxiv, and bioRxiv from 3 February 2020 to 31 December 2020, and they were reviewed by title, abstract, and text for relevance. The literature search indicated that COVID-19 patients frequently present with gustatory dysfunction, xerostomia, and oral mucosal lesions, while their prevalence is likely to vary by country, age, gender, and disease severity. Gustatory dysfunction and xerostomia appear at an early stage of SARS-CoV-2 infection and last relatively long. One of possible pathogenic mechanisms of both symptoms is attributed to the expression of viral cellular entry-relevant receptors in taste cells and salivary glands. Dental professionals who can first become aware of oral symptoms associated with COVID-19 will play a more active role in and make a greater contribution to diagnosis and prevention of COVID-19.

Chemosensory Systems in COVID-19: Evolution of Scientific Research

COVID-19 disease induced by coronavirus SARS-CoV-2 presents among its symptoms alterations of the chemosensory functions. In the first studies on the Chinese population, this symptomatology was not particularly relevant, and hyposmia and hypogeusia were excluded from the symptoms to be evaluated to diagnose the disease. With the pandemic spread of the illness, there has been an augment in reports on chemosensory dysfunctions among patients. The first data analysis showed the presence of these disorders mainly in paucisymptomatic and asymptomatic patients. The interest in chemosensory systems therefore increased considerably, because the olfactory and gustatory symptoms could be the key to stop the infection spread. Furthermore, the degree of alert and attention grew, considering that these types of dysfunctions are prognostic symptoms of serious neurodegenerative diseases. About 9 months have passed since the first anecdotal reports on the involvement of the olfactory and gustatory systems in the COVID-19 pathology. For this reason, a careful review of the literature was conducted to understand if it is clearer which people present chemosensory symptoms and if these are related to the severity of the disease. Furthermore, we have identified which aspects still remain to be clarified.

Smell and Taste Loss Recovery Time in COVID-19 Patients and Disease Severity

A significant proportion of people infected with SARS-CoV-2 report a new onset of smell or taste loss. The duration of the chemosensory impairment and predictive factors of recovery are still unclear. We aimed to investigate the prevalence, temporal course and recovery predictors in patients who suffered from varying disease severity. Consecutive adult patients diagnosed to be infected with SARS-CoV-2 via reverse-transcription–polymerase chain reaction (RT-PCR) at two coronavirus disease-2019 (COVID-19) Reference Hospitals were contacted to complete a survey reporting chemosensory loss, severity, timing and duration, nasal symptoms, smoking, allergic rhinitis, chronic rhinosinusitis, comorbidities and COVID-19 severity. In a cross-sectional study, we contacted 182 patients and 150 responded. Excluding the critically ill patients, 38% reported gustatory and 41% olfactory impairment (74% severe/anosmia). Most of the patients (88%) recovered their sense of smell by two months (median: 11.5 days; IQR: 13.3). For 23%, the olfactory loss lasted longer than a month. There were no significant differences in the prevalence and duration of chemosensory loss between groups of varying COVID-19 severity, and sexes (all p > 0.05). Moderate hyposmia resolved quicker than more severe loss (p = 0.04). Smell and taste loss are highly prevalent in COVID-19. Most patients recover fast, but nearly one out of ten have not recovered in two months.

[Chemosensory disorders in Covid-19: Pathomechanisms and clinical relevance]

In this review article, current information on the frequency and relevance of chemosensory disorders in Covid-19 was recorded, assigned pathophysiologically and statements on prognostic significance were derived. The results are based on a comprehensive literature search of all literature on this topic and our own experience in the treatment of patients with smell and taste disorders since the beginning of the pandemic.Current study results indicate that clinically less affected Covid-19 patients without inpatient treatment and who do not require ventilation often have disorders of the chemosensory system. In young patients and women in particular, they seem to be an indicator of a favorable prognosis for the course of the disease. Smell disorders can appear early, as the sole symptom or together with other symptoms of Covid-19 disease. It has not yet been clarified whether ageusia can occur independently or whether it is also felt in the context of anosmia. In the pandemic, the new occurrence of anosmia without congestion / obstruction/runny nose is probably an expression of an infection with SARS-CoV-2 and should always give rise to quarantine and testing for SARS-CoV-2. The smell disorder in Covid-19 mostly seems to be temporary; It is not yet possible to conclusively assess whether there is usually a full restitution. The therapeutic approaches already established for other postviral olfactory disorders (e. g. olfactory training) are also used here.

Stringent thresholds in SARS-CoV-2 IgG assays lead to under-detection of mild infections

BACKGROUND

Thresholds for SARS-CoV-2 antibody assays have typically been determined using samples from symptomatic, often hospitalised, patients. In this setting the sensitivity and specificity of the best performing assays can both exceed 98%. However, antibody assay performance following mild infection is less clear.

METHODS

We assessed quantitative IgG responses in a cohort of healthcare workers in Oxford, UK, with a high pre-test probability of Covid-19, in particular the 991/11,475(8.6%) who reported loss of smell/taste. We use anosmia/ageusia and other risk factors as probes for Covid-19 infection potentially undiagnosed by immunoassays by investigating their relationship with antibody readings either side of assay thresholds.

RESULTS

The proportion of healthcare workers reporting anosmia/ageusia increased at antibody readings below diagnostic thresholds using an in-house ELISA (n = 9324) and the Abbott Architect chemiluminescent microparticle immunoassay (CMIA; n = 11,324): 426/906 (47%) reported anosmia/ageusia with a positive ELISA, 59/449 (13.1%) with high-negative and 326/7969 (4.1%) with low-negative readings. Similarly, by CMIA, 518/1093 (47.4%) with a positive result reported anosmia/ageusia, 106/686 (15.5%) with a high-negative and 358/9563 (3.7%) with a low-negative result. Adjusting for the proportion of staff reporting anosmia/ageusia suggests the sensitivity of both assays in mild infection is lower than previously reported: Oxford ELISA 89.8% (95%CI 86.6-92.8%) and Abbott CMIA 79.3% (75.9-82.7%).

CONCLUSION

Following mild SARS-CoV-2 infection 10-30% of individuals may have negative immunoassay results. While lowered diagnostic thresholds may result in unacceptable specificity, our findings have implications for epidemiological analyses and result interpretation in individuals with a high pre-test probability. Samples from mild PCR-confirmed infections should be included in SARS-CoV-2 immunoassay evaluations.

Loss of Smell and Taste Can Accurately Predict COVID-19 Infection: A Machine-Learning Approach

The COVID-19 outbreak has spread extensively around the world. Loss of smell and taste have emerged as main predictors for COVID-19. The objective of our study is to develop a comprehensive machine learning (ML) modelling framework to assess the predictive value of smell and taste disorders, along with other symptoms, in COVID-19 infection. A multicenter case-control study was performed, in which suspected cases for COVID-19, who were tested by real-time reverse-transcription polymerase chain reaction (RT-PCR), informed about the presence and severity of their symptoms using visual analog scales (VAS). ML algorithms were applied to the collected data to predict a COVID-19 diagnosis using a 50-fold cross-validation scheme by randomly splitting the patients in training (75%) and testing datasets (25%). A total of 777 patients were included. Loss of smell and taste were found to be the symptoms with higher odds ratios of 6.21 and 2.42 for COVID-19 positivity. The ML algorithms applied reached an average accuracy of 80%, a sensitivity of 82%, and a specificity of 78% when using VAS to predict a COVID-19 diagnosis. This study concludes that smell and taste disorders are accurate predictors, with ML algorithms constituting helpful tools for COVID-19 diagnostic prediction.

Chemosensory Dysfunction in Patients with COVID-19: What Do We Learn from the Global Outbreak?

PURPOSE OF REVIEW

Chemosensory dysfunction in the patients with COVID-19 has been reported frequently in the studies from different regions of the world. However, the prevalence of smell and/or taste disorders presents significant ethnic and geographic variability. In addition, the pathogenesis of chemosensory dysfunction remains unclarified.

RECENT FINDINGS

This is a narrative review on the recent state of the prevalence, mechanism, and diagnostic and therapeutic strategy of chemosensory dysfunction in COVID-19 patients during the global pandemic. The chemosensory dysfunction was analysis based on recent studies, which either used questionnaires, Likert scales (0-10), or smell tests to estimate the smell and taste dysfunction. The ethnic and geographic difference of the prevalence of smell and/or taste disorders and the potential underlying mechanisms have been discussed. Several suggestions on the diagnosis and treatment of COVID-19 patients with smell and taste disorders were summarized for the physicians. This review provides a comprehensive overview of the current studies regarding the chemosensory dysfunction during the COVID-19 worldwide outbreak.

COVID 19-Induced Smell and Taste Impairments: Putative Impact on Physiology

Smell and taste impairments are recognized as common symptoms in COVID 19 patients even in an asymptomatic phase. Indeed, depending on the country, in up to 85-90% of cases anosmia and dysgeusia are reported. We will review briefly the main mechanisms involved in the physiology of olfaction and taste focusing on receptors and transduction as well as the main neuroanatomical pathways. Then we will examine the current evidences, even if still fragmented and unsystematic, explaining the disturbances and mode of action of the virus at the level of the nasal and oral cavities. We will focus on its impact on the peripheral and central nervous system. Finally, considering the role of smell and taste in numerous physiological functions, especially in ingestive behavior, we will discuss the consequences on the physiology of the patients as well as management regarding food intake.

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.

Olfactory Dysfunction in COVID-19 Patients: Findings from a Tertiary Rural Centre

Olfactory and/or taste dysfunction are potential neurological manifestations of coronavirus disease -2019 (COVID-19). The aim of the study was to document the prevalence of anosmia in COVID-19 positive patients and analyze the effect of various factors on the occurrence of these chemosensory dysfunction in the local population. Tertiary referral center. Prospective Study. 250 subjects who tested positive for SARS-CoV-2, by real-time polymerase chain reaction (RT-PCR) and admitted in Isolation ward were enrolled for the study. Data was collected from the subjects via oral questionnaire method, based on the AAO-HNS Anosmia Reporting Tool. Data was collected regarding the age, gender, olfactory or gustatory disturbances, history of recent travel or contact with a positive case, smoking, any associated symptoms, any co-morbid conditions and recovery time of sense of olfaction. Out of 250, 179 (71.6%) subjects were diagnosed with Olfactory dysfunction out of which majority were males, 105 (58.6%). Most of the patients were above 40 years of age (n = 184, 73.6%). Majority of the individuals (88 patients) had close contact with a positive case in recent past, followed by 67 patients who were health care workers, hence proving that risk of infection increases with exposure. Anosmia was present in 68.5% of all the 127 non-smokers. 66.4% had both olfactory as well as gustatory dysfunction whereas 18 patients (7.2%) were found to be totally asymptomatic. Mostly patients recovered their sense of smell within 1-2 weeks from the day of onset of anosmia. Presence of olfactory dysfunction of any degree with or without alteration in taste sensation should raise a suspicion of COVID-19 infection, especially when other classical signs are not present. In such conditions, swabs should be sent for confirmation by RT-PCR testing and till results are awaited, the individual should be shifted to quarantine facilities or advised strict self-isolation.

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.

SARS-CoV-2 infections among healthcare workers at Helsinki University Hospital, Finland, spring 2020: Serosurvey, symptoms and risk factors

Background

Exposure, risks and immunity of healthcare workers (HCWs), a vital resource during the SARS-CoV-2 pandemic, warrant special attention.

Methods

HCWs at Helsinki University Hospital, Finland, filled in questionnaires and provided serum samples for SARS-CoV-2-specific antibody screening by Euroimmun IgG assay in March–April 2020. Positive/equivocal findings were confirmed by Abbott and microneutralization tests. Positivity by two of the three assays or RT-PCR indicated a Covid-19 case (CoV+).

Results

The rate of CoV(+) was 3.3% (36/1095) and seropositivity 3.0% (33/1095). CoV(+) was associated with contact with a known Covid-19 case, and working on a Covid-19-dedicated ward or one with cases among staff. The rate in the Covid-19-dedicated ICU was negligible. Smoking and age <55 years were associated with decreased risk. CoV(+) was strongly associated with ageusia, anosmia, myalgia, fatigue, fever, and chest pressure. Seropositivity was recorded for 89.3% of those with prior documented RT-PCR-positivity and 2.4% of those RT-PCR-negative. The rate of previously unidentified cases was 0.7% (8/1067) and asymptomatic ones 0% (0/36).

Conclusion

Undiagnosed and asymptomatic cases among HCWs proved rare. An increased risk was associated with Covid-19-dedicated wards. Particularly high rates were seen for wards with liberal HCW-HCW contacts, highlighting the importance of social distancing also among HCWs.

Self-reported smell and taste alteration as the sole clinical manifestation of SARS-CoV-2 infection

Chemosensory dysfunction has increasingly been reported in patients with coronavirus disease 2019 (COVID-19). Here, we document a case of a patient with taste and smell alterations as the only clinical manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In March 2020, a 36-year-old woman presented with self-reported hypogeusia/ageusia and hyposmia/anosmia in the absence of any respiratory symptom. The patient, who had no clinical and radiographic signs of sinusitis and was otherwise healthy, eventually had a positive test result for SARS-CoV-2. She did not develop any COVID-19–related symptoms throughout her 6-month follow up. Her self-reported chemosensory dysfunction lasted for 12 weeks. To the best of our knowledge, this is the first report that has accurately documented taste and smell alteration as the sole manifestation of COVID-19 in an otherwise healthy individual. Overall, analysis of current evidence supports the inclusion of gustatory and olfactory alterations as cardinal symptoms of COVID-19. Dentists’ awareness of the diagnostic criteria for case definition of COVID-19 can facilitate early detection of the disease.

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.

Olfactory and taste dysfunction among mild-to-moderate symptomatic COVID-19 positive health care workers: An international survey

OBJECTIVES

To determine the prevalence of olfactory and taste dysfunction (OD; TD) among COVID-19 positive health care workers (HCWs), their associated risk factors and prognosis.

METHODS

Between May and June 2020, a longitudinal multicenter study was conducted on symptomatic COVID-19 PCR confirmed HCWs (COVID-19 positive) in London and Padua.

RESULTS

Hundred and fourteen COVID-19 positive HCWs were surveyed with a response rate of 70.6% over a median follow-up period of 52 days. UK prevalence of OD and TD was 73.1% and 69.2%, respectively. There was a male to female ratio of 1:3 with 81.6% being white, 43.7% being nurses/health care assistants (HCAs), and 39.3% being doctors. In addition, 53.2% of them worked on COVID-19 wards. Complete recovery was reported in 31.8% for OD and 47.1% for TD with a 52 days follow-up. The job role of doctors and nurses negatively influenced smell (P = .04 and P = .02) and taste recovery (P = .02 and P = .01). Ethnicity (being white) showed to positively influence only taste recovery (P = .04). Sex (being female) negatively influenced OD and TD recovery only in Paduan HCWs (P = .02 and P = .011, respectively). Working on a COVID-19 ward did not influence prognosis.

CONCLUSIONS

The prevalence of OD and TD was considerably higher in HCWs. The prognosis for OD and TD recovery was worse for nurses/HCAs and doctors but working on a COVID-19 ward did not influence prognosis. Sixty-eight percent of surveyed HCWs at 52 days continued to experience OD or TD requiring additional future medical management capacity.

LEVEL OF EVIDENCE

4.

Environmental Issues and Neurological Manifestations Associated with COVID-19 Pandemic: New Aspects of the Disease?

Coronavirus (SARS-CoV-2) emerged in China in December 2019 and rapidly caused a global health pandemic. Current evidence seems to suggest a possible link with ecosystem disequilibrium and even air pollution. The primary manifestations affect respiratory and circulatory systems, but neurological features are also being reported through case reports and case series. We summarize neurological symptoms and complications associated with COVID-19. We have searched for original articles published in PubMed/Medline, PubMed Central and Google Scholar using the following keywords: "COVID-19", "Coronavirus", "pandemic", "SARS-COV-2", "neurology", "neurological", "complications" and "manifestations". We found around 1000 publications addressing the issue of neurological conditions associated with COVID-19 infection. Amongst those, headache and dizziness are the most common reported symptoms followed by encephalopathy and delirium, while the most frequent complications are cerebrovascular accidents, Guillain-Barré syndrome, acute transverse myelitis, and acute encephalitis. Specific symptoms affecting the peripheral nervous system such as hyposmia and dysgeusia are the most common manifestations recorded in the selected studies. Interestingly, it was noted that these kinds of neurological symptoms might precede the typical features, such as fever and cough, in COVID patients. Neurological symptoms and complications associated with COVID-19 should be considered as a part of the clinical features of this novel global pandemic.

Gastrointestinal Manifestations and Associated Health Outcomes of COVID-19: A Brazilian Experience From the Largest South American Public Hospital

OBJECTIVES

Brazil has rapidly developed the second-highest number of COVID-19 cases in the world. As such, proper symptom identification, including gastrointestinal manifestations, and relationship to health outcomes remains key. We aimed to assess the prevalence and impact of gastrointestinal symptoms associated with COVID-19 in a large quaternary referral center in South America.

METHODS

This was a single-center cohort study in a COVID-19 specific hospital in São Paulo, Brazil. Consecutive adult patients with laboratory confirmed SARS-CoV-2 were included. Baseline patient history, presenting symptoms, laboratory results, and clinically relevant outcomes were recorded. Regression analyses were performed to determine significant predictors of the gastrointestinal manifestations of COVID-19 and hospitalization outcomes.

RESULTS

Four-hundred patients with COVID-19 were included. Of these, 33.25% of patients reported ≥1 gastrointestinal symptom. Diarrhea was the most common gastrointestinal symptom (17.25%). Patients with gastrointestinal symptoms had higher rates of concomitant constitutional symptoms, notably fatigue and myalgia (p<0.05). Gastrointestinal symptoms were also more prevalent among patients on chronic immunosuppressants, ACE/ARB medications, and patient with chronic kidney disease (p<0.05). Laboratory results, length of hospitalization, ICU admission, ICU length of stay, need for mechanical ventilation, vasopressor support, and in-hospital mortality did not differ based upon gastrointestinal symptoms (p>0.05). Regression analyses showed older age [OR 1.04 (95% CI, 1.02-1.06)], male gender [OR 1.94 (95% CI, 1.12-3.36)], and immunosuppression [OR 2.60 (95% CI, 1.20-5.63)], were associated with increased mortality.

CONCLUSION

Based upon this Brazilian study, gastrointestinal manifestations of COVID-19 are common but do not appear to impact clinically relevant hospitalization outcomes including the need for ICU admission, mechanical ventilation, or mortality.

Chemosensory Dysfunction in COVID-19: Integration of Genetic and Epidemiological Data Points to D614G Spike Protein Variant as a Contributing Factor

After several months of rapid pandemic expansion, it is now apparent that the SARS-CoV-2 coronavirus interferes with smell and taste sensation in a substantial proportion of COVID-19 patients. Recent epidemiological data documented intriguing differences in prevalence of chemosensory dysfunctions between different world regions. Viral genetic factors as well as host genetic factors appear to be relevant; however, it is not yet known which mutations or polymorphisms actually contribute to such phenotypic differences between populations. Here, we discuss recent genetic and epidemiological data on the D614G spike protein variant and assess whether current evidence is consistent with the notion that this single nucleotide polymorphism augments chemosensory impairments in COVID-19 patients. We hypothesize that this spike variant is an important viral genetic factor that facilitates infection of chemosensory epithelia, possibly acting together with yet to be identified host factors, and thereby increases smell and taste impairment. We suggest that the prevalence of chemosensory deficits may reflect the pandemic potential for transmissibility and spread which differs between populations.

Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19: An evidence-based clinical practice guideline (updated version)

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.

Anosmia in COVID-19: A Bumpy Road to Establishing a Cellular Mechanism

It has become clear since the pandemic broke out that SARS-CoV-2 virus causes reduction of smell and taste in a significant fraction of COVID-19 patients. The olfactory dysfunction often occurs early in the course of the disease, and sometimes it is the only symptom in otherwise asymptomatic carriers. The cellular mechanisms for these specific olfactory disturbances in COVID-19 are now beginning to be elucidated. Several very recent papers contributed to explaining the key cellular steps occurring in the olfactory epithelium leading to anosmia/hyposmia (collectively known as dysosmia) initiated by SARS-CoV-2 infection. In this Viewpoint, we discuss current progress in research on olfactory dysfunction in COVID-19 and we also propose an updated model of the SARS-CoV-2-induced dysosmia. The emerging central role of sustentacular cells and inflammatory processes in the olfactory epithelium are particularly considered. The proposed model of anosmia in COVID-19 does not answer unequivocally whether the new coronavirus exploits the olfactory route to rapidly or slowly reach the brain in COVID-19 patients. To answer this question, new systematic studies using an infectious virus and appropriate animal models are needed.

The clinical course of smell and taste loss in COVID-19 hospitalized patients

BACKGROUND

Recent studies have demonstrated an association between a new onset of smell or taste loss and COVID-19. We investigated the prevalence of smell and/or taste loss and the clinical characteristics and recovery in a comprehensive cohort of consecutive patients treated by two COVID-19 reference hospitals and evaluated late persistence of hyposmia.

METHODS

A retrospective observational questionnaire study was conducted. All consecutive RT-PCR diagnosed patients who had been hospitalized in March-April 2020 in the COVID-19 care wards were contacted, excluding patients with cognitive disorders and severe deconditioning. The patients responded to a survey about the loss of smell and taste, nasal blockage, and rhinorrhea, rated the symptoms' severity from 0 to 4, and reported the recovery of smell and taste with time. Demographic and clinical characteristics were recorded.

RESULTS

We contacted 117 patients. Ninety responded to the questionnaire; 38.9 % of them reported olfactory and 36.66 % gustatory disorders during their disease. Smell loss prior to other symptoms was reported by 42.86 %, and severe hyposmia/anosmia by 74.28 % of the hyposmic. Among the non-ICU treated patients, 43.75 % reported hyposmia. Only 8.89 % had nasal blockage, and 6.66 % rhinorrhea. Most of the patients (85.71 %) recovered their sense of smell in 3-61 days (median: 17; IQR: 24), but 8.57 % had persistent hyposmia. For one out of four, the olfactory loss lasted longer than a month.

CONCLUSION

Smell and taste loss are highly prevalent and early symptoms in hospitalized COVID-19 patients. The great majority recover their smell, but nearly one out of ten have not recovered in two months.  HIPPOKRATIA 2020, 24(2): 66-71.