“Anosmia” the mysterious collateral damage of COVID-19

Maximizing Participation in Olfactory Training in a Sample with Post-COVID-19 Olfactory Loss

PURPOSE

This study aims to highlight the feasibility of an olfactory training program entirely monitored through online media in COVID-19 patients.

METHODS

Classic olfactory training was performed with a sample with olfactory loss due COVID-19 (n = 11). Participants were engaged on a weekly video call in order to improve adherence and collect information regarding the number of correct answers and the individuals' perception of olfactory function. The olfactory status after training was compared to two groups, one composed of participants who contracted COVID-19 but did not report olfactory loss (n = 11) and a sample composed of healthy participants (n = 11).

RESULTS

The experimental group showed improvements throughout the training period (TDI score on week 0 was 20.3 (5.6) and 24.6 (4.3) for week 12, and on week 24 was 25.4 (6.2) (F = 5.115, df = 2, 20, p = 0.016), and post hoc tests showed that participants significantly improved their TDI score in W12 compared to W0 (SMD = 0.869, p = 0.041) and in W24 compared to W0 (SMD = 0.859, p = 0.041). The experimental group showed lower scores when compared with both groups, and the no OT COVID-19 group showed lower scores than the healthy control group, even though they did not report olfactory alterations.

CONCLUSIONS

Findings suggest that the strategies applied to improve adherence were successful since 100% of the sample completed the training adherence, offering a valuable framework for future olfactory training studies.

Reduced olfactory bulb volume accompanies olfactory dysfunction after mild SARS-CoV-2 infection

Despite its high prevalence, the determinants of smelling impairment in COVID-19 remain not fully understood. In this work, we aimed to examine the association between olfactory bulb volume and the clinical trajectory of COVID-19-related smelling impairment in a large-scale magnetic resonance imaging (MRI) analysis. Data of non-vaccinated COVID-19 convalescents recruited within the framework of the prospective Hamburg City Health Study COVID Program between March and December 2020 were analyzed. At baseline, 233 participants underwent MRI and neuropsychological testing as well as a structured questionnaire for olfactory function. Between March and April 2022, olfactory function was assessed at follow-up including quantitative olfactometric testing with Sniffin' Sticks. This study included 233 individuals recovered from mainly mild to moderate SARS-CoV-2 infections. Longitudinal assessment demonstrated a declining prevalence of self-reported olfactory dysfunction from 67.1% at acute infection, 21.0% at baseline examination and 17.5% at follow-up. Participants with post-acute self-reported olfactory dysfunction had a significantly lower olfactory bulb volume at baseline than normally smelling individuals. Olfactory bulb volume at baseline predicted olfactometric scores at follow-up. Performance in neuropsychological testing was not significantly associated with the olfactory bulb volume. Our work demonstrates an association of long-term self-reported smelling dysfunction and olfactory bulb integrity in a sample of individuals recovered from mainly mild to moderate COVID-19. Collectively, our results highlight olfactory bulb volume as a surrogate marker that may inform diagnosis and guide rehabilitation strategies in COVID-19.

Prevalence and Factors Associated with Olfactory Dysfunction in Individuals with COVID-19 in Brazil: A Study of 20,669 Cases from 2020 to 2021

OBJECTIVE

The aim of the study is to determine the prevalence and factors associated with olfactory dysfunction in individuals with COVID-19 in the first 2 years of the pandemic in Brazil.

MATERIALS AND METHODS

This is a prevalent study involving the confirmed cases of COVID-19 recorded in the municipality between the years 2020 and 2021. Individuals symptomatic for COVID-19, with a positive laboratory result and aged 12 or older were included in this study. Measures of central tendency and dispersion were used in the description of continuous variables and frequency was used for categorical variables. The Shapiro-Wilk test was used to evaluate data distribution.

RESULTS

Data from 20,669 individuals were analyzed. The prevalence of olfactory disorders was 17.9% and increased from 11.5% to 21.9% between 2020 and 2021. A female gender predominance was observed among individuals who reported anosmia, with 61.1% (n = 564) in 2020 and 61.7% (n = 1,713) in 2021. On the other hand, the median age of individuals with olfactory disorders was lower than that of the group without disorders (35 [IQR 27-46] vs. 39 [IQR 29-50]; p < 0.001). Smell disturbances were present in 18.2% (n = 3,634) of patients who recovered and in 7.1% (n = 38) of those who died. Furthermore, in 2021, a prevalence rate of 30.6% for olfactory disorders was linked to obesity as a comorbidity.

CONCLUSION

The prevalence of olfactory disorders was lower compared to other studies, with cough and fever being negatively related to olfactory dysfunction and headache, coryza, and taste disorders being positively related. Obesity was the only associated comorbidity.

Mechanism and treatment of olfactory dysfunction caused by coronavirus disease 2019

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the start of the pandemic, olfactory dysfunction (OD) has been reported as a common symptom of COVID-19. In some asymptomatic carriers, OD is often the first and even the only symptom. At the same time, persistent OD is also a long-term sequela seen after COVID-19 that can have a serious impact on the quality of life of patients. However, the pathogenesis of post-COVID-19 OD is still unclear, and there is no specific treatment for its patients. The aim of this paper was to review the research on OD caused by SARS-CoV-2 infection and to summarize the mechanism of action, the pathogenesis, and current treatments.

Understanding olfactory dysfunction in the COVID-19 era: insights from a cross-sectional survey of the Saudi community

Background and objectives

COVID-19 has emerged as a public health emergency caused by the coronavirus 2 (SARS-CoV2). However, only a few studies have reported that anosmia is an early predictor of COVID-19. Therefore, this study aimed to assess the current level of knowledge regarding smell dysfunction in COVID-19 era in Saudi community.

Materials and methods

An online survey was conducted using Survey Monkeys in Saudi Arabia. The survey was distributed through Twitter and WhatsApp. The questionnaire included individuals' demographic information, such as sex, age, residence, income, and qualifications, as well as their knowledge of the early symptoms of COVID-19. ANOVA and Mann-Whitney U-test were conducted to analyze the data. There were twelve items on knowledge dimensions which were assessed through five-point Likert scale.

Results

In total, 809 respondents completed the questionnaire. Among them, 658 (81.3%) had no knowledge of how sudden loss of or change in the sense of smell can be the only symptom of COVID-19. However, most participants, 738 (91.2%), knew that fever was a symptom of COVID-19. Similarly, 707 (87.4%) and 772 (95.5%) participants knew that cough and shortness of breath were the major symptoms of COVID-19, respectively. In addition, 395 (48.3%) participants had no information regarding taste changes as a symptom of COVID-19. Notably, participants who were female, married, or diagnosed with COVID-19 had significantly greater knowledge of smell-related issues due to COVID-19 than males, unmarried, and healthy/those without COVID-19.

Conclusion

This study revealed that the Saudi population has an fairly good level of knowledge regarding common COVID-19 symptoms as more than 90% of the participants understood symptoms of COVID-19, but less acceptable knowledge regarding smell and taste dysfunction as more than 80% had no knowledge of change in olfactory and taste function was due to COVID-19.

Prevalence of Self-Reported Anosmia and Ageusia in Elderly Patients Who Had Been Previously Hospitalized by SARS-CoV-2: The LONG-COVID-EXP Multicenter Study

We explored two different graph methods for visualizing the prevalence of self-reported post-COVID anosmia and ageusia in a large sample of individuals who had been previously hospitalized in five different hospitals. A cohort of 1266 previously hospitalized COVID-19 survivors participated. Participants were assessed at hospitalization (T0) and at three different follow-up periods: 8.4 (T1), 13.2 (T2), and 18.3 (T3) months after hospital discharge. They were asked about the presence of self-reported anosmia and ageusia that they attributed to infection. Anosmia was defined as a self-perceived feeling of complete loss of smell. Ageusia was defined as a self-perceived feeling of complete loss of taste. Data about hospitalization were recorded from medical records. The results revealed that the prevalence of anosmia decreased from 8.29% (n = 105) at hospitalization (T0), to 4.47% (n = 56) at T1, to 3.27% (n = 41) at T2, and 3.35% (n = 42) at T3. Similarly, the prevalence of ageusia was 7.10% (n = 89) at the onset of SARS-CoV-2 infection (T0), but decreased to 3.03% (n = 38) at T1, to 1.99% (n = 25) at T2, and 1.36% (n = 17) at T3. The Sankey plots showed that only 10 (0.8%) and 11 (0.88%) patients exhibited anosmia and ageusia throughout all the follow-ups. The exponential curves revealed a progressive decrease in prevalence, demonstrating that self-reported anosmia and ageusia improved in the years following hospitalization. The female sex (OR4.254, 95% CI 1.184-15.294) and sufferers of asthma (OR7.086, 95% CI 1.359-36.936) were factors associated with the development of anosmia at T2, whereas internal care unit admission was a protective factor (OR0.891, 95% CI 0.819-0.970) for developing anosmia at T2. The use of a graphical method, such as a Sankey plot, shows that post-COVID self-reported anosmia and ageusia exhibit fluctuations during the first years after SARS-CoV-2 infection. Additionally, self-reported anosmia and ageusia also show a decrease in prevalence during the first years after infection, as expressed by exponential bar plots. The female sex was associated with the development of post-COVID anosmia, but not ageusia, in our cohort of elderly patients previously hospitalized due to COVID-19.

Risks and Preventions for Pregnant Women and Their Preterm Infants in a World with COVID-19: A Narrative Review

(1) Background and Aim: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is linked to increasing cases of coronavirus disease 2019 (COVID-19) around the world. COVID-19 infections have an important impact on pregnancy, preterm birth (PTB) and delivery. Although several complications have been reported in infected pregnant women, the effect of infection on PTB is controversial. The purpose of this study was to summarize the existing literature on the effects and complications of COVID-19 on the health of pregnant women and preterm babies and its impact on the incidence of PTB. We also discuss the effect of current COVID-19 vaccines during pregnancy. (2) Methods: We carried out a systematic search of MEDLINE, Embase, and PubMed for studies on preterm births associated with COVID-19. (3) Results and Conclusions: We discovered contradictory results regarding the prevalence of PTB during the pandemic compared to earlier years. While most studies indicated an increase in PTBs with COVID-19, some indicated a decline in the preterm delivery rate during this time. During pregnancy, COVID-19 infection can increase the incidence of cesarean section, stillbirth, ICU admission, preeclampsia/eclampsia, and mortality rates. In the treatment of pregnant women with severe COVID-19, methylprednisolone was favored over prednisolone, and a brief course of dexamethasone is advised for pregnant women with anticipated PTB to accelerate the development of the fetal lung. Generally, vaccination for COVID-19 in pregnant and lactating women stimulates anti-SARS-CoV2 immune responses, and it does not result in any noteworthy negative reactions or outcomes for the mother or baby.

Negative correlation between ACE2 gene expression levels and loss of taste in a cohort of COVID-19 hospitalized patients: New clues to long-term cognitive disorders

In early 2020, one of the most prevalent symptoms of SARS-CoV-2 infection was the loss of smell (anosmia), found in 60-70% of all cases. Anosmia used to occur early, concomitantly with other symptoms, and often persisted after recovery for an extended period, sometimes for months. In addition to smell disturbance, COVID-19 has also been associated with loss of taste (ageusia). The latest research suggests that SARS-CoV-2 could spread from the respiratory system to the brain through receptors in sustentacular cells localized to the olfactory epithelium. The virus invades human cells via the obligatory receptor, angiotensin-converting enzyme II (ACE2), and a priming protease, TMPRSS2, facilitating viral penetration. There is an abundant expression of both ACE2 and TMPRSS2 in sustentacular cells. In this study, we evaluated 102 COVID-19 hospitalized patients, of which 17.60% presented anosmia and 9.80% ageusia. ACE1, ACE2, and TMPRSS2 gene expression levels in nasopharyngeal tissue were obtained by RT-qPCR and measured using ΔCT analysis. ACE1 Alu287bp association was also evaluated. Logistic regression models were generated to estimate the effects of variables on ageusia and anosmia Association of ACE2 expression levels with ageusia. was observed (OR: 1.35; 95% CI: 1.098-1.775); however, no association was observed between TMPRSS2 and ACE1 expression levels and ageusia. No association was observed among the three genes and anosmia, and the Alu287bp polymorphism was not associated with any of the outcomes. Lastly, we discuss whetherthere is a bridge linking these initial symptoms, including molecular factors, to long-term COVID-19 health consequences such as cognitive dysfunctions.

The prevalence of sensory changes in post-COVID syndrome: A systematic review and meta-analysis

Post-COVID syndrome can be defined as symptoms of COVID-19 that persist for longer than 12 weeks, with several studies reporting persistent symptoms relating to the sensory organs (eyes, ears, and nose). The aim of this systematic review was to examine the prevalence of persistent anosmia, hyposmia, ageusia, and hypogeusia, as well as eye/vision and ear/hearing related long-COVID symptoms. Authors searched the electronic databases from inception to November 2021. Search terms included words related to long-COVID, smell, taste, eyes/vision, and ears/hearing, with all observational study designs being included. A random effects meta-analysis was undertaken, calculating the prevalence proportions of anosmia, hyposmia, ageusia, and hypogeusia, respectively. From the initial pool, 21 studies met the inclusion criteria (total n 4,707; median n per study 125; median age = 49.8; median percentage female = 59.2%) and 14 were included in the meta-analysis The prevalence of anosmia was 12.2% (95% CI 7.7–16.6%), hyposmia 29.9% (95% CI 19.9–40%), ageusia 11.7% (95% CI 6.1–17.3%), and hypogeusia 31.2% (95% 16.4–46.1%). Several eye/vision and ear/hearing symptoms were also reported. Considering that changes in the sensory organs are associated with decreases in quality of life, future research should examine the etiology behind the persistent symptoms.

Assessment of Smell and Taste Disturbances among COVID-19 Convalescent Patients: A Cross-Sectional Study in Armenia

Background and Objectives: Neurological manifestations of Coronavirus Disease 2019 (COVID-19) such as olfactory and gustatory disturbance have been reported among convalescent COVID-19 patients. However, scientific data on the prevalence of smell and taste disturbance are lacking. Therefore, we present findings on the degree of smell and taste disturbances among the Armenian population. Methods: Study participants were randomly recruited and then categorized into two groups based on their course of the disease. A cross-sectional study was performed to assess participants’ sensitivity to smell triggered by the olfactory and the trigeminal nerves; their ability to differentiate between various odors; and to evaluate their gustatory perception. Results: The smell test revealed that the degree of olfactory nerve disturbance was different by 30.7% in those participants of the early group as compared to those of the late group, and the degree of trigeminal nerve disturbance was different by 71.3% in the early group as compared to the late group. A variation of the differentiating ability among the participants of the early and late groups was detected. Gustatory disturbances for all flavors were also found to be different in both the groups. A moderate positive correlation (0.51) was found between the overall sensitivity of smell and the ability to differentiate between various odors as cumulatively stimulated by both the olfactory and trigeminal nerves. Also, a moderate positive correlation (0.33) was found between headache and smell sensitivity through the olfactory nerve and a high negative correlation (−0.71) was found between headache and smell sensitivity through the trigeminal nerve. Conclusion: Pathological changes in the olfactory and trigeminal perceptive abilities caused disturbances in smell sensation, with the trigeminal nerve being more affected. The capacity to differentiate fragrances did not improve with time and the disturbance severity of bitter taste perception was higher among the study participants.