Post-COVID-19 Syndrome Mechanisms, Prevention and Management.

As the population of patients recovering from COVID-19 grows, post COVID-19 challenges are recognizing by ongoing evidences at once. Long COVID is defined as a syndrome with a range of persistent symptoms that remain long after (beyond 12 weeks) the acute SARS-CoV-2 infection. Studies have shown that long COVID can cause multi-organ damages with a wide spectrum of manifestations. Many systems, but not limited to, including respiratory, cardiovascular, nervous, gastrointestinal, and musculoskeletal systems, are involved in long COVID. Fatigue and dyspnea are the most common symptoms of long COVID. Long COVID-19 may be driven by tissue damage caused by virus-specific pathophysiologic changes or secondary to pathological long-lasting inflammatory response because of viral persistence, immune dysregulation, and autoimmune reactions. Some risk factors like sex and age, more than five early symptoms, and specific biomarkers have been revealed as a probable long COVID predicator discussed in this review. It seems that vaccination is the only way for prevention of long COVID and it can also help patients who had already long COVID. Managing long COVID survivors recommended being in a multidisciplinary approach, and a framework for identifying those at high risk for post-acute COVID-19 must be proposed. Possible therapeutic options and useful investigation tools for follow-up are suggested in this review. In sum, as evidence and researches are regularly updated, we provide the current understanding of the epidemiology, clinical manifestation, suspected pathophysiology, associated risk factors, and treatment options of long COVID in this review.

Cognitive and functional connectivity impairment in post-COVID-19 olfactory dysfunction.

OBJECTIVES: To explore the neuropsychological profile and the integrity of the olfactory network in patients with COVID-19-related persistent olfactory dysfunction (OD). METHODS: Patients with persistent COVID-19-related OD underwent olfactory assessment with Sniffin' Sticks and neuropsychological evaluation. Additionally, both patients and a control group underwent brain MRI, including T1-weighted and resting-state functional MRI (rs-fMRI) sequences on a 3 T scanner. Morphometrical properties were evaluated in olfaction-associated regions; the rs-fMRI data were analysed using graph theory at the whole-brain level and within a standard parcellation of the olfactory functional network. All the MR-derived quantities were compared between the two groups and their correlation with clinical scores in patients were explored. RESULTS: We included 23 patients (mean age 37 ± 14 years, 12 females) with persistent (mean duration 11 ± 5 months, range 2-19 months) COVID-19-related OD (mean score 23.63 ± 5.32/48, hyposmia cut-off: 30.75) and 26 sex- and age-matched healthy controls. Applying population-derived cut-off values, the two cognitive domains mainly impaired were visuospatial memory and executive functions (17 % and 13 % of patients). Brain MRI did not show gross morphological abnormalities. The lateral orbital cortex, hippocampus, and amygdala volumes exhibited a reduction trend in patients, not significant after the correction for multiple comparisons. The olfactory bulb volumes did not differ between patients and controls. Graph analysis of the functional olfactory network showed altered global and local properties in the patients' group (n = 19, 4 excluded due to artifacts) compared to controls. Specifically, we detected a reduction in the global modularity coefficient, positively correlated with hyposmia severity, and an increase of the degree and strength of the right thalamus functional connections, negatively correlated with short-term verbal memory scores. DISCUSSION: Patients with persistent COVID-19-related OD showed an altered olfactory network connectivity correlated with hyposmia severity and neuropsychological performance. No significant morphological alterations were found in patients compared with controls.

The presence of symptoms within 6 months after COVID-19: a single-center longitudinal study.

BACKGROUND: Characterizing the post-COVID health conditions is helpful to direct patients to appropriate healthcare. AIMS: To describe the presence of symptoms in COVID-19 patients within 6 months after diagnosis and to investigate the associated factors in terms of reporting symptoms. METHODS: Data of DEU-COVIMER (a telephone interview-based COVID-19 follow-up center established in a tertiary care hospital) was analyzed for SARS-CoV-2 RNA positive participants aged ≥ 18 years from November 1st, 2020, to May 31st, 2021. Symptom frequencies were stratified by demographic and clinical characteristics at one, three, and 6 months after diagnosis. With the patients who had symptoms at baseline, generalized estimating equations were applied to identify the factors associated with reporting of symptoms. RESULTS: A total of 5610 patients agreed to participate in the study. Symptom frequency was 37.2%, 21.8%, and 18.2% for the first, third, and sixth months. Tiredness/fatigue, muscle or body aches, and dyspnea/difficulty breathing were the most common symptoms in all time frames. In multivariate analysis, older age, female gender (odds ratio OR 1.74, 95% confidence interval 1.57-1.93), bad economic status (OR 1.37, 1.14-1.65), current smoking (OR 1.15, 1.02-1.29), being fully vaccinated before COVID-19 (OR 0.53, 0.40-0.72), having more health conditions (≥ 3 conditions, OR 1.78, 1.33-2.37), having more symptoms (> 5 symptoms, OR 2.47, 2.19-2.78), and hospitalization (intensive care unit, OR 2.18, 1.51-3.14) were associated with reporting of symptoms. CONCLUSIONS: This study identifies risk factors for patients who experience post-COVID-19 symptoms. Healthcare providers should appropriately allocate resources prioritizing the patients who would benefit from post-COVID rehabilitation.

Validation Criteria for PETCO2 Kinetics during the Hyperventilation Provocation Test in the Diagnosis of Idiopathic Hyperventilation Syndrome.

BACKGROUND: The hyperventilation provocation test (HPTest) is a diagnostic tool for idiopathic hyperventilation syndrome (HVS), encountered in some long-COVID patients. However, interpretation of the HPTest remains unclear regarding the relevant PETCO2 values to focus on and whether subjective symptoms should be considered. This study aimed to re-evaluate objective HPTest results for diagnosing HVS by determining accurate PETCO2 kinetics in two groups of patients previously screened via the Nijmegen questionnaire (NQ). METHODS: The kinetics of PETCO2 during the HPTest were mathematically modeled and compared between 37 HVS patients (NQ ≥23/64) and 37 healthy controls (NQ <23/64) matched for gender, age, and body dimensions. AUC values with sensitivity and specificity were calculated, and analysis was monitored in a validation cohort of 152 routine HPTests. RESULTS: A threshold value of a less than 12.8 mmHg increment of PETCO2 at the 5th minute of the recovery phase of the HPTest diagnosed HVS patients with excellent sensitivity (0.92) and specificity (0.84). These results were confirmed in the validation cohort, highlighting the presence of 24% false positives/negatives when diagnosing on the basis of complaints in the NQ. CONCLUSIONS: For HVS diagnosis, we suggest considering the HPTest, which can more reliably reflect the mechanisms of CO2 homeostasis and the response of the respiratory center to a stimulus, regardless of the subjective onset of symptoms.

High prevalence of persistent symptoms and reduced health-related quality of life 6 months after COVID-19.

Background: The long-term sequelae after COVID-19 constitute a challenge to public health and increased knowledge is needed. We investigated the prevalence of self-reported persistent symptoms and reduced health-related quality of life (HRQoL) in relation to functional exercise capacity, 6 months after infection, and explored risk factors for COVID-19 sequalae. Methods: This was a prospective, multicenter, cohort study including 434 patients. At 6 months, physical exercise capacity was assessed by a 1-minute sit-to-stand test (1MSTST) and persistent symptoms were reported and HRQoL was evaluated through the EuroQol 5-level 5-dimension (EQ-5D-5L) questionnaire. Patients with both persistent symptoms and reduced HRQoL were classified into a new definition of post-acute COVID syndrome, PACS+. Risk factors for developing persistent symptoms, reduced HRQoL and PACS+ were identified by multivariable Poisson regression. Results: Persistent symptoms were experienced by 79% of hospitalized, and 59% of non-hospitalized patients at 6 months. Hospitalized patients had a higher prevalence of self-assessed reduced overall health (28 vs. 12%) and PACS+ (31 vs. 11%). PACS+ was associated with reduced exercise capacity but not with abnormal pulse/desaturation during 1MSTST. Hospitalization was the most important independent risk factor for developing persistent symptoms, reduced overall health and PACS+. Conclusion: Persistent symptoms and reduced HRQoL are common among COVID-19 survivors, but abnormal pulse and peripheral saturation during exercise could not distinguish patients with PACS+. Patients with severe infection requiring hospitalization were more likely to develop PACS+, hence these patients should be prioritized for clinical follow-up after COVID-19.

Short and mid-term characteristics of COVID-19 disease course in athletes: A high-volume, single-center study.

INTRODUCTION: At the pandemic's beginning, significant concern has risen about the prevalence of myocardial involvement after SARS-CoV-2 infection. We assessed the cardiovascular burden of SARS-CoV-2 in a large cohort of athletes and identified factors that might affect the disease course. We included 633 athletes in our study on whom we performed extensive cardiology examinations after recovering from SARS-CoV-2 infection. More than half of the athletes (n = 322) returned for a follow-up examination median of 107 days after the commencement of their infection. RESULTS: Troponin T positivity was as low as 1.4% of the athletes, where the subsequently performed examinations did not show definitive, ongoing myocardial injury. Altogether, 31% of the athletes' rapid training rebuild was hindered by persistent or reoccurring symptoms. Female athletes reported a higher prevalence of return to play (RTP) symptoms than their male counterparts (34% vs. 19%, p = 0.005). The development of long COVID symptoms was independently predicted by increasing age and acute symptoms' severity in a multiple regression model (AUC 0.75, CI 0.685-0.801). Athletes presenting with either or both cough and ferritin levels higher than >150 µg/L had a 4.1x (CI 1.78-9.6, p = 0.001) higher odds ratio of developing persistent symptoms. CONCLUSION: While SARS-CoV-2 rarely affects the myocardium in athletes, about one in three of them experience symptoms beyond the acute phase. Identifying those athletes with a predisposition to developing long-standing symptoms may aid clinicians and trainers in finding the optimal return-to-play timing and training load rebuild pace.

Neurocognitive and Psychosocial Characteristics of Pediatric Patients With Post-Acute/Long-COVID: A Retrospective Clinical Case Series.

OBJECTIVE: Studies suggest a large number of patients have persistent symptoms following COVID-19 infection-a condition termed "long COVID." Although children and parents often report cognitive difficulties after COVID, very few if any studies have been published including neuropsychological testing. METHODS: A retrospective chart review was completed for the first 18 patients referred for a neuropsychological evaluation from a multidisciplinary pediatric post-COVID clinic. The neuropsychological screening battery assessed verbal fluency and category switching, attention, working memory, processing speed, and verbal learning and memory. Patients' caregivers also completed standardized questionnaires regarding day-to-day mood and behavior. RESULTS: At intake, the most common neurologic symptoms reported by caregivers were attention problems (83.3%), fatigue/lethargy (77.7%), sleep disturbance (77.7%), dizziness/vertigo (72.2%), and headaches (72.2%). On rating scales, most caregivers endorsed concerns for depressed mood and anxiety (14/15 and 12/15). A large proportion of patients had difficulties with attention (9/18) and depressed mood/anxiety (13/18) before COVID. On cognitive testing, the majority of the patients performed within or above broad average range (≥16th percentile) across most domains. However, a little over half of the patients performed below average on auditory attention measures. CONCLUSIONS: Within our clinically referred sample, children who reported lingering cognitive symptoms after COVID-19 often had a preexisting history of attention and/or mood and anxiety concerns. Many of these patients performed below average in attention testing, but it remains to be seen whether this was due to direct effects of COVID, physical symptoms, and/or preexisting difficulties with attention or mood/anxiety.

Long COVID and its Management.

The pandemic of COVID-19 is the biggest public health crisis in 21st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.

Remodeling of T Cell Dynamics During Long COVID Is Dependent on Severity of SARS-CoV-2 Infection.

Several COVID-19 convalescents suffer from the post-acute COVID-syndrome (PACS)/long COVID, with symptoms that include fatigue, dyspnea, pulmonary fibrosis, cognitive dysfunctions or even stroke. Given the scale of the worldwide infections, the long-term recovery and the integrative health-care in the nearest future, it is critical to understand the cellular and molecular mechanisms as well as possible predictors of the longitudinal post-COVID-19 responses in convalescent individuals. The immune system and T cell alterations are proposed as drivers of post-acute COVID syndrome. However, despite the number of studies on COVID-19, many of them addressed only the severe convalescents or the short-term responses. Here, we performed longitudinal studies of mild, moderate and severe COVID-19-convalescent patients, at two time points (3 and 6 months from the infection), to assess the dynamics of T cells immune landscape, integrated with patients-reported symptoms. We show that alterations among T cell subsets exhibit different, severity- and time-dependent dynamics, that in severe convalescents result in a polarization towards an exhausted/senescent state of CD4+ and CD8+ T cells and perturbances in CD4+ Tregs. In particular, CD8+ T cells exhibit a high proportion of CD57+ terminal effector cells, together with significant decrease of naïve cell population, augmented granzyme B and IFN-γ production and unresolved inflammation 6 months after infection. Mild convalescents showed increased naïve, and decreased central memory and effector memory CD4+ Treg subsets. Patients from all severity groups can be predisposed to the long COVID symptoms, and fatigue and cognitive dysfunctions are not necessarily related to exhausted/senescent state and T cell dysfunctions, as well as unresolved inflammation that was found only in severe convalescents. In conclusion, the post-COVID-19 functional remodeling of T cells could be seen as a two-step process, leading to distinct convalescent immune states at 6 months after infection. Our data imply that attenuation of the functional polarization together with blocking granzyme B and IFN-γ in CD8+ cells might influence post-COVID alterations in severe convalescents. However, either the search for long COVID predictors or any treatment to prevent PACS and further complications is mandatory in all patients with SARS-CoV-2 infection, and not only in those suffering from severe COVID-19.

Unbalanced IDO1/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia.

Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome's evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.

Evidence mapping and review of long-COVID and its underlying pathophysiological mechanism.

PURPOSE: Apart from the global disease burden of acute COVID-19 disease, the health complications arising after recovery have been recognized as a long-COVID or post-COVID-19 syndrome. Evidences of long-COVID symptoms involving various organ systems are rapidly growing in literature. The objective was to perform a rapid review and evidence mapping of systemic complications and symptoms of long-COVID and underlying pathophysiological mechanisms. METHODS: Publications reporting clinical trials, observational cohort studies, case-control studies, case-series, meta-analysis, and systematic reviews, focusing on the squeal of the disease, consequences of COVID-19 treatment/hospitalization, long-COVID, chronic COVID syndrome, and post acute COVID-19 were reviewed in detail for the narrative synthesis of frequency, duration, risk factors, and pathophysiology. RESULTS: The review highlights that pulmonary, neuro-psychological, and cardiovascular complications are major findings in most epidemiological studies. However, dysfunctional gastrointestinal, endocrine, and metabolic health are recent findings for which underlying pathophysiological mechanisms are poorly understood. Analysis of the clinical trial landscape suggests that more than 50% of the industry-sponsored trials are focused on pulmonary symptoms. In contrast to the epidemiological trends and academic trials, cardiovascular complications are not a focus of industry-sponsored trials, suggestive of the gaps in the research efforts. CONCLUSION: The gap in epidemiological trends and academic trials, particularly concerning cardiovascular complications not being a focus of industry-sponsored trials is suggestive of the gaps in research efforts and longer follow-up durations would help identify other long-COVID-related health issues such as reproductive health and fertility.

Early clues regarding the pathogenesis of long-COVID.

Intense investigation into the predictors and determinants of post-acute sequelae of SARS-CoV-2 infection (PASC), including 'long COVID', is underway. Recent studies provide clues to the mechanisms that might drive this condition, with the goal of identifying host or virus factors that can be intervened upon to prevent or reverse PASC.

Associations of Post-Acute COVID syndrome with physiological and clinical measures 10 months after hospitalization in patients of the first wave.

BACKGROUND: For a better understanding of the factors underlying the Post-Acute COVID Syndrome, we studied the relationship between symptoms and functional alterations in COVID-19 patients 10 months after hospitalization. METHODS: One-hundred-one patients hospitalized between March 1st and June 30th 2020 participated in a follow-up visit for an assessment of clinical history, comorbidities, lung function, physical capacity and symptoms, including the SGRQ for health-related quality of life, PHQ-9-D for depression, and SOMS-2 J for somatoform disorders. Data were analyzed by univariate comparisons and multiple logistic regression analyses. RESULTS: Median age was 60 years, 42% were female, 76% had at least one comorbidity, the median length of the hospital stay was 8 days, 19% had been on the ICU. The most prevalent symptoms included shortness of breath (49%), fatigue (49%) and cognitive impairment (39%). Signs of major depression (PHQ-9-D ≥ 10) occurred in 28%/2% (p < 0.05) of patients with/without self-reported cognitive impairment, with median total SGRQ score being 25.4/5.3 (p < 0.05). There were associations between shortness of breath and BMI, SGRQ and hemoglobin levels; between fatigue, SGRQ and PHQ-9-D; and between cognitive impairment and PHQ-9-D (p < 0.05 each) but not with lung function or physical capacity. Characteristics of the acute disease were not related to symptoms. CONCLUSIONS: The findings demonstrate that 10 months after discharge from a hospital stay due to COVID-19, the percentages of patients with symptoms were high. Symptoms showed a consistent pattern but could not be attributed to altered lung function or physical capacity. Our results suggest a role for alternative etiologies including psychosocial factors.

More Than 100 Persistent Symptoms of SARS-CoV-2 (Long COVID): A Scoping Review.

Background: Persistent coronavirus disease 2019 (COVID-19) symptoms are increasingly well-reported in cohort studies and case series. Given the spread of the pandemic, number of individuals suffering from persistent symptoms, termed 'long COVID', are significant. However, type and prevalence of symptoms are not well reported using systematic literature reviews. Objectives: In this scoping review of the literature, we aggregated type and prevalence of symptoms in people with long COVID. Eligibility Criteria: Original investigations concerning the name and prevalence of symptoms were considered in participants ≥4-weeks post-infection. Sources of Evidence: Four electronic databases [Medline, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL)] were searched. Methods: A scoping review was conducted using the Arksey and O'Malley framework. Review selection and characterisation was performed by three independent reviewers using pretested forms. Results: Authors reviewed 2,711 titles and abstracts for inclusion with 152 selected for full-text review. 102 articles were subsequently removed as this did not meet inclusion criteria. Thus, fifty studies were analysed, 34 of which were described as cohort studies or prospective cohort studies, 14 were described as cross-sectional studies, one was described as a case control study, and one was described as a retrospective observational study. In total, >100 symptoms were identified and there was considerable heterogeneity in symptom prevalence and setting of study. Ten studies reported cardiovascular symptoms, four examined pulmonary symptoms, 25 reported respiratory symptoms, 24 reported pain-related symptoms, 21 reported fatigue, 16 reported general infection symptoms, 10 reported symptoms of psychological disorders, nine reported cognitive impairment, 31 reported a sensory impairment, seven reported a dermatological complaint, 11 reported a functional impairment, and 18 reported a symptom which did not fit into any of the above categories. Conclusion: Most studies report symptoms analogous to those apparent in acute COVID-19 infection (i.e., sensory impairment and respiratory symptoms). Yet, our data suggest a larger spectrum of symptoms, evidenced by >100 reported symptoms. Symptom prevalence varied significantly and was not explained by data collection approaches, study design or other methodological approaches, and may be related to unknown cohort-specific factors.