Efficacy and tolerability of an endogenous metabolic modulator (AXA1125) in fatigue-predominant long COVID: a single-centre, double-blind, randomised controlled phase 2a pilot study

Overview of methods that determine mitochondrial function in human disease

Cellular metabolism has a key role in the pathogenesis of human disease. Mitochondria are the organelles that generate most of the energy needed for a cell to function and drive cellular metabolism. Understanding the link between metabolic and mitochondrial function can be challenging due to the variation in methods used to measure mitochondrial function and heterogeneity in mitochondria, cells, tissues, and end organs. Mitochondrial dysfunction can be determined at both the cellular and tissue levels using several methods, such as assessment of cellular bioenergetics, levels of mitochondrial DNA (mtDNA), mitochondrial membrane potential (MMP), mitochondrial reactive oxygen species (mito-ROS), and levels of mitochondrial enzymes. Recent advances involving novel radiotracers in combination with PET imaging have allowed for the determination of mitochondrial function in vivo with high specificity. Understanding the barriers in existing methodologies used to study mitochondrial function may help further establish the assessment of mitochondrial function as a biologically and clinically relevant biomarker for human disease severity and prognosis. Herein, we critically review the existing literature regarding the strengths and limitations of methods that determine mitochondrial function, and we subsequently discuss how emerging research methods have begun to overcome some of these hurdles. We conclude that a combination of techniques, including respirometry and mitochondrial membrane potential assessment, is necessary to understand the complexity and biological and clinical relevance of mitochondrial function in human disease.

Novel biomarkers of mitochondrial dysfunction in Long COVID patients

Coronavirus disease 2019 (COVID-19) can lead to severe acute respiratory syndrome, and while most individuals recover within weeks, approximately 30-40% experience persistent symptoms collectively known as Long COVID, post-COVID-19 syndrome, or post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC). These enduring symptoms, including fatigue, respiratory difficulties, body pain, short-term memory loss, concentration issues, and sleep disturbances, can persist for months. According to recent studies, SARS-CoV-2 infection causes prolonged disruptions in mitochondrial function, significantly altering cellular energy metabolism. Our research employed transmission electron microscopy to reveal distinct mitochondrial structural abnormalities in Long COVID patients, notably including significant swelling, disrupted cristae, and an overall irregular morphology, which collectively indicates severe mitochondrial distress. We noted increased levels of superoxide dismutase 1 which signals oxidative stress and elevated autophagy-related 4B cysteine peptidase levels, indicating disruptions in mitophagy. Importantly, our analysis also identified reduced levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in these patients, serving as a novel biomarker for the condition. These findings underscore the crucial role of persistent mitochondrial dysfunction in the pathogenesis of Long COVID. Further exploration of the cellular and molecular mechanisms underlying post-viral mitochondrial dysfunction is critical, particularly to understand the roles of autoimmune reactions and the reactivation of latent viruses in perpetuating these conditions. This comprehensive understanding could pave the way for targeted therapeutic interventions designed to alleviate the chronic impacts of Long COVID. By utilizing circulating ccf-mtDNA and other novel mitochondrial biomarkers, we can enhance our diagnostic capabilities and improve the management of this complex syndrome.

Dysregulation of lipid metabolism, energy production, and oxidative stress in myalgic encephalomyelitis/chronic fatigue syndrome, Gulf War Syndrome and fibromyalgia

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), Gulf War Syndrome (GWS), and Fibromyalgia (FM) are complex, chronic illnesses with overlapping clinical features. Symptoms that are reported across these conditions include post-exertional malaise (PEM), fatigue, and pain, yet the etiology of these illnesses remains largely unknown. Diagnosis is challenging in patients with these conditions as definitive biomarkers are lacking; patients are required to meet clinical criteria and often undergo lengthy testing to exclude other conditions, a process that is often prolonged, costly, and burdensome for patients. The identification of reliable validated biomarkers could facilitate earlier and more accurate diagnosis and drive the development of targeted pharmacological therapies that might address the underlying pathophysiology of these diseases. Major driving forces for biomarker identification are the advancing fields of metabolomics and proteomics that allow for comprehensive characterization of metabolites and proteins in biological specimens. Recent technological developments in these areas enable high-throughput analysis of thousands of metabolites and proteins from a variety of biological samples and model systems, that provides a powerful approach to unraveling the metabolic phenotypes associated with these complex diseases. Emerging evidence suggests that ME/CFS, GWS, and FM are all characterized by disturbances in metabolic pathways, particularly those related to energy production, lipid metabolism, and oxidative stress. Altered levels of key metabolites in these pathways have been reported in studies highlighting potential common biochemical abnormalities. The precise mechanisms driving altered metabolic pathways in ME/CFS, GWS, and FM remain to be elucidated; however, the elevated oxidative stress observed across these illnesses may contribute to symptoms and offer a potential target for therapeutic intervention. Investigating the mechanisms, and their role in the disease process, could provide insights into disease pathogenesis and reveal novel treatment targets. As such, comprehensive metabolomic and proteomic analyses are crucial for advancing the understanding of these conditions in-order to identify both common, and unique, metabolic alterations that could serve as diagnostic markers or therapeutic targets.

Interventions for Long COVID: A Narrative Review

Long COVID continues to impose a significant burden on COVID-19 survivors, presenting with diverse symptoms and clinical uncertainty. This review synthesized evidence from 97 studies, including 26 randomized controlled trials and 15 non-randomized comparative studies, which explored the effectiveness, comparative effectiveness, and potential risks of proposed interventions for managing common long COVID symptoms: fatigue, neurocognitive symptoms, anxiety, depression, and sleep issues. Our comprehensive analysis, encompassing English-language articles, gray literature, and feedback from 14 Key Informants (i.e., patients, caregivers, clinicians, payors, and researchers), reveals a persistently weak body of evidence, characterized by high imprecision and considerable uncertainty regarding the benefits and harms of the interventions. The studies examined a wide array of treatment categories, including multi-component rehabilitation, supplements, complementary treatments, prescription medications, and the COVID-19 vaccine. Key informants emphasized the critical need for establishing robust diagnostic criteria and utilizing functional outcomes while also highlighting significant barriers to care, including dismissive attitudes from healthcare providers, inadequate insurance coverage, and restricted access to specialty care. Given the evolving definitions of long COVID and the variable mechanisms of its management, our findings underscore the pressing need for further rigorous research to refine and validate effective treatment protocols. Until more definitive evidence is available, both clinicians and patients face substantial uncertainty in treatment decisions, with many resorting to self-treatment using costly and potentially ineffective options.

Neurovascular dysregulation in systemic sclerosis: novel insights into pathophysiology, diagnosis, and treatment utilizing invasive cardiopulmonary exercise testing

PURPOSE OF REVIEW

Pathologic abnormalities in skeletal muscle and the systemic vasculature are common in patients with systemic sclerosis (SSc). These abnormalities may lead to impaired systemic peripheral oxygen extraction (EO 2 ), known as neurovascular dysregulation, which may be because of abnormal blood flow distribution in the vasculature, microvascular shunting, and/or skeletal muscle mitochondrial dysfunction. Findings from invasive cardiopulmonary exercising testing (iCPET) provide important insights and enable diagnosis and treatment of this SSc disease manifestation.

RECENT FINDINGS

Recent findings from noninvasive cardiopulmonary exercise testing (niCPET) support the existence of neurovascular dysregulation in patients with SSc. Invasive cardiopulmonary exercise testing (iCPET) has pointed to reduced systemic vascular distensibility as a possible mechanism for neurovascular dysregulation in patients with connective tissue diseases, including SSc.

SUMMARY

Neurovascular dysregulation is likely an underappreciated cause of exercise impairment and dyspnea in patients with SSc in the presence or absence of underlying cardiopulmonary disease. It is posited to be related to microcirculatory and muscle dysfunction. Further studies are needed to clarify the pathophysiology of neurovascular dysregulation in SSc and to identify novel treatment targets and additional therapies.

1H and 31P MR Spectroscopy to Assess Muscle Mitochondrial Dysfunction in Long COVID

Background Emerging evidence suggests mitochondrial dysfunction may play a role in the fatigue experienced by individuals with post-COVID-19 condition (PCC), commonly called long COVID, which can be assessed using MR spectroscopy. Purpose To compare mitochondrial function between participants with fatigue-predominant PCC and healthy control participants using MR spectroscopy, and to investigate the relationship between MR spectroscopic parameters and fatigue using the 11-item Chalder fatigue questionnaire. Materials and Methods This prospective, observational, single-center study (June 2021 to January 2024) included participants with PCC who reported moderate to severe fatigue, with normal blood test and echocardiographic results, alongside control participants without fatigue symptoms. MR spectroscopy was performed using a 3-T MRI system, measuring hydrogen 1 (1H) and phosphorus 31 (31P) during exercise and recovery in the gastrocnemius muscle. General linear models were used to compare the phosphocreatine recovery rate time constant (hereafter, τPCr) and maximum oxidative flux, also known as mitochondrial capacity (hereafter, Qmax), between groups. Pearson correlations were used to assess the relationship between MR spectroscopic parameters and fatigue scores. Results A total of 41 participants with PCC (mean age, 44 years ± 9 [SD]; 23 male) (mean body mass index [BMI], 26 ± 4) and 29 healthy control participants (mean age, 34 years ± 11; 18 male) (mean BMI, 23 ± 3) were included in the study. Participants with PCC showed higher resting phosphocreatine levels (mean difference, 4.10 mmol/L; P = .03). Following plantar flexion exercise in situ (3-5 minutes), participants with PCC had a higher τPCr (92.5 seconds ± 35.3) compared with controls (51.9 seconds ± 31.9) (mean difference, 40.6; 95% CI: 24.3, 56.6; P ≤ .001), and Qmax was higher in the control group, with a mean difference of 0.16 mmol/L per second (95% CI: 0.07, 0.26; P = .008). There was no correlation between MR spectroscopic parameters and fatigue scores (r ≤ 0.25 and P ≥ .10 for all). Conclusion Participants with PCC showed differences in τPCr and Qmax compared with healthy controls, suggesting potential mitochondrial dysfunction. This finding did not correlate with fatigue scores. Published under a CC BY 4.0 license. Supplemental material is available for this article. See also the editorial by Parraga and Eddy in this issue.

Translating insights into therapies for Long Covid

Long Covid is defined by a wide range of symptoms that persist after the acute phase of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Commonly reported symptoms include fatigue, weakness, postexertional malaise, and cognitive dysfunction, with many other symptoms reported. Symptom range, duration, and severity are highly variable and partially overlap with symptoms of myalgic encephalomyelitis/chronic fatigue syndrome and other post-acute infectious syndromes, highlighting opportunities to define shared mechanisms of pathogenesis. Potential mechanisms of Long Covid are diverse, including persistence of viral reservoirs, dysregulated immune responses, direct viral damage of tissues targeted by SARS-CoV-2, inflammation driven by reactivation of latent viral infections, vascular endothelium activation or dysfunction, and subsequent thromboinflammation, autoimmunity, metabolic derangements, microglial activation, and microbiota dysbiosis. The heterogeneity of symptoms and baseline characteristics of people with Long Covid, as well as the varying states of immunity and therapies given at the time of acute infection, have made etiologies of Long Covid difficult to determine. Here, we examine progress on preclinical models for Long Covid and review progress being made in clinical trials, highlighting the need for large human studies and further development of models to better understand Long Covid. Such studies will inform clinical trials that will define treatments to benefit those living with this condition.

Mechanisms of long COVID and the path toward therapeutics

Long COVID, a type of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC) defined by medically unexplained symptoms following infection with SARS-CoV-2, is a newly recognized infection-associated chronic condition that causes disability in some people. Substantial progress has been made in defining its epidemiology, biology, and pathophysiology. However, there is no cure for the tens of millions of people believed to be experiencing long COVID, and industry engagement in developing therapeutics has been limited. Here, we review the current state of knowledge regarding the biology and pathophysiology of long COVID, focusing on how the proposed mechanisms explain the physiology of the syndrome and how they provide a rationale for the implementation of a broad experimental medicine and clinical trials agenda. Progress toward preventing and curing long COVID and other infection-associated chronic conditions will require deep and sustained investment by funders and industry.

Mitochondrial dysfunction in long COVID: mechanisms, consequences, and potential therapeutic approaches

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has introduced the medical community to the phenomenon of long COVID, a condition characterized by persistent symptoms following the resolution of the acute phase of infection. Among the myriad of symptoms reported by long COVID sufferers, chronic fatigue, cognitive disturbances, and exercise intolerance are predominant, suggesting systemic alterations beyond the initial viral pathology. Emerging evidence has pointed to mitochondrial dysfunction as a potential underpinning mechanism contributing to the persistence and diversity of long COVID symptoms. This review aims to synthesize current findings related to mitochondrial dysfunction in long COVID, exploring its implications for cellular energy deficits, oxidative stress, immune dysregulation, metabolic disturbances, and endothelial dysfunction. Through a comprehensive analysis of the literature, we highlight the significance of mitochondrial health in the pathophysiology of long COVID, drawing parallels with similar clinical syndromes linked to post-infectious states in other diseases where mitochondrial impairment has been implicated. We discuss potential therapeutic strategies targeting mitochondrial function, including pharmacological interventions, lifestyle modifications, exercise, and dietary approaches, and emphasize the need for further research and collaborative efforts to advance our understanding and management of long COVID. This review underscores the critical role of mitochondrial dysfunction in long COVID and calls for a multidisciplinary approach to address the gaps in our knowledge and treatment options for those affected by this condition.

Lithium Aspartate for Long COVID Fatigue and Cognitive Dysfunction: A Randomized Clinical Trial

Importance

Neurologic post-COVID-19 condition (PCC), or long COVID, symptoms of fatigue and cognitive dysfunction continue to affect millions of people who have been infected with SARS-CoV-2. There currently are no effective evidence-based therapies available for treating neurologic PCC.

Objective

To assess the effects of lithium aspartate therapy on PCC fatigue and cognitive dysfunction.

Design, Setting, and Participants

A randomized, double-blind, placebo-controlled trial (RCT) enrolling participants in a neurology clinic from November 28, 2022, to June 29, 2023, with 3 weeks of follow-up, was conducted. Subsequently, an open-label lithium dose-finding study with 6 weeks of follow-up was performed among the same participants enrolled in the RCT. Eligible individuals needed to report new, bothersome fatigue or cognitive dysfunction persisting for more than 4 weeks after a self-reported positive test for COVID-19, Fatigue Severity Scale-7 (FSS-7) or Brain Fog Severity Scale (BFSS) score of 28 or greater, Beck Depression Inventory-II score less than 24, and no history of a condition known to cause fatigue or cognitive dysfunction. All participants in the RCT were eligible for the dose-finding study, except for those who responded to the placebo. Intention-to-treat analysis was used.

Intervention

Lithium aspartate, 10 to 15 mg/d, or identically appearing placebo for 3 weeks followed by open-label lithium aspartate, 10 to 15 mg/d, for 2 weeks. In the subsequent dose-finding study, open-label lithium aspartate dosages up to 45 mg/d for 6 weeks were given.

Main Outcomes and Measures

Change in sum of FSS-7 and BFSS scores. The scores for each measure range from 7 to 49, with higher scores indicating more severe symptoms. Secondary outcomes included changes from baseline in the scores of additional questionnaires.

Results

Fifty-two participants were enrolled (30 [58%] males; mean [SD] age, 58.54 [14.34] years) and 26 were randomized to treatment with lithium aspartate (10 females) and 26 to placebo (12 female). Two participants assigned to lithium aspartate were lost to follow-up and none withdrew. No adverse events were attributable to lithium therapy. There were no significant intergroup differences for the primary outcome (-3.6; 95% CI, -16.6 to 9.5; P = .59) or any secondary outcomes. Among 3 patients completing a subsequent dose-finding study, open-label lithium aspartate, 40 to 45 mg/d, was associated with numerically greater reductions in fatigue and cognitive dysfunction scores than 15 mg/d, particularly in 2 patients with serum lithium levels of 0.18 and 0.49 mEq/L compared with 1 patient with a level of 0.10 mEq/L.

Conclusions and Relevance

In this RCT, therapy with lithium aspartate, 10 to 15 mg/d, was ineffective for neurologic PCC fatigue and cognitive dysfunction. Another RCT is required to assess the potential benefits of higher lithium dosages for treating neurologic PCC.

Trial Registration

ClinicalTrials.gov Identifier: NCT05618587 and NCT06108297.

1-year health outcomes associated with systemic corticosteroids for COVID-19: a longitudinal cohort study

Background

In patients with coronavirus disease 2019 (COVID-19) requiring supplemental oxygen, dexamethasone reduces acute severity and improves survival, but longer-term effects are unknown. We hypothesised that systemic corticosteroid administration during acute COVID-19 would be associated with improved health-related quality of life (HRQoL) 1 year after discharge.

Methods

Adults admitted to hospital between February 2020 and March 2021 for COVID-19 and meeting current guideline recommendations for dexamethasone treatment were included using two prospective UK cohort studies (Post-hospitalisation COVID-19 and the International Severe Acute Respiratory and emerging Infection Consortium). HRQoL, assessed by the EuroQol-Five Dimensions-Five Levels utility index (EQ-5D-5L UI), pre-hospital and 1 year after discharge were compared between those receiving corticosteroids or not after propensity weighting for treatment. Secondary outcomes included patient-reported recovery, physical and mental health status, and measures of organ impairment. Sensitivity analyses were undertaken to account for survival and selection bias.

Findings

Of the 1888 participants included in the primary analysis, 1149 received corticosteroids. There was no between-group difference in EQ-5D-5L UI at 1 year (mean difference 0.004, 95% CI -0.026-0.034). A similar reduction in EQ-5D-5L UI was seen at 1 year between corticosteroid exposed and nonexposed groups (mean±sd change -0.12±0.22 versus -0.11±0.22). Overall, there were no differences in secondary outcome measures. After sensitivity analyses modelled using a cohort of 109 318 patients admitted to hospital with COVID-19, EQ-5D-5L UI at 1 year remained similar between the two groups.

Interpretation

Systemic corticosteroids for acute COVID-19 have no impact on the large reduction in HRQoL 1 year after hospital discharge. Treatments to address the persistent reduction in HRQoL are urgently needed.

Post-Acute Sequelae and Mitochondrial Aberration in SARS-CoV-2 Infection

This review investigates links between post-acute sequelae of SARS-CoV-2 infection (PASC), post-infection viral persistence, mitochondrial involvement and aberrant innate immune response and cellular metabolism during SARS-CoV-2 infection. Advancement of proteomic and metabolomic studies now allows deeper investigation of alterations to cellular metabolism, autophagic processes and mitochondrial dysfunction caused by SARS-CoV-2 infection, while computational biology and machine learning have advanced methodologies of predicting virus-host gene and protein interactions. Particular focus is given to the interaction between viral genes and proteins with mitochondrial function and that of the innate immune system. Finally, the authors hypothesise that viral persistence may be a function of mitochondrial involvement in the sequestration of viral genetic material. While further work is necessary to understand the mechanisms definitively, a number of studies now point to the resolution of questions regarding the pathogenesis of PASC.

Long COVID as a disease of accelerated biological aging: An opportunity to translate geroscience interventions

It has been four years since long COVID-the protracted consequences that survivors of COVID-19 face-was first described. Yet, this entity continues to devastate the quality of life of an increasing number of COVID-19 survivors without any approved therapy and a paucity of clinical trials addressing its biological root causes. Notably, many of the symptoms of long COVID are typically seen with advancing age. Leveraging this similarity, we posit that Geroscience-which aims to target the biological drivers of aging to prevent age-associated conditions as a group-could offer promising therapeutic avenues for long COVID. Bearing this in mind, this review presents a translational framework for studying long COVID as a state of effectively accelerated biological aging, identifying research gaps and offering recommendations for future preclinical and clinical studies.

Evaluating myelophil, a 30% ethanol extract of Astragalus membranaceus and Salvia miltiorrhiza, for alleviating fatigue in long COVID: a real-world observational study

Background

Persistent post-infectious symptoms, predominantly fatigue, characterize Long COVID. This study investigated the efficacy of Myelophil (MYP), which contains metabolites extracted from Astragalus membranaceus and Salvia miltiorrhiza using 30% ethanol, in alleviating fatigue among subjects with Long COVID.

Methods

In this prospective observational study, we enrolled subjects with significant fatigue related to Long COVID, using criteria of scores of 60 or higher on the modified Korean Chalder Fatigue scale (mKCFQ11), or five or higher on the Visual Analog Scale (VAS) for brain fog. Utilizing a single-arm design, participants were orally administered MYP (2,000 mg daily) for 4 weeks. Changes in fatigue severity were assessed using mKCFQ11, Multidimensional Fatigue Inventory (MFI-20), and VAS for fatigue and brain fog. In addition, changes in quality of life using the short form 12 (SF-12) were also assessed along with plasma cortisol levels.

Results

A total of 50 participants (18 males, 32 females) were enrolled; 49 were included in the intention-to-treat analysis with scores of 66.9 ± 11.7 on mKCFQ11 and 6.3 ± 1.5 on the brain fog VAS. After 4 weeks of MYP administration, there were statistically significant improvements in fatigue levels: mKCFQ11 was measured at 34.8 ± 17.1 and brain fog VAS at 3.0 ± 1.9. Additionally, MFI-20 decreased from 64.8 ± 9.8 to 49.3 ± 10.8, fatigue VAS dropped from 7.4 ± 1.0 to 3.4 ± 1.7, SF-12 scores rose from 53.3 ± 14.9 to 78.6 ± 14.3, and plasma cortisol levels also elevated from 138.8 ± 50.1 to 176.9 ± 62.0 /mL. No safety concerns emerged during the trial.

Conclusion

Current findings underline MYP's potential in managing Long COVID-induced fatigue. However, comprehensive studies remain imperative.

Clinical Trial Registration

https://cris.nih.go.kr, identifier KCT0008948.

Long COVID and cardiovascular disease: a prospective cohort study

BACKGROUND

Pre-existing cardiovascular disease (CVD) or cardiovascular risk factors have been associated with an increased risk of complications following hospitalisation with COVID-19, but their impact on the rate of recovery following discharge is not known.

OBJECTIVES

To determine whether the rate of patient-perceived recovery following hospitalisation with COVID-19 was affected by the presence of CVD or cardiovascular risk factors.

METHODS

In a multicentre prospective cohort study, patients were recruited following discharge from the hospital with COVID-19 undertaking two comprehensive assessments at 5 months and 12 months. Patients were stratified by the presence of either CVD or cardiovascular risk factors prior to hospitalisation with COVID-19 and compared with controls with neither. Full recovery was determined by the response to a patient-perceived evaluation of full recovery from COVID-19 in the context of physical, physiological and cognitive determinants of health.

RESULTS

From a total population of 2545 patients (38.8% women), 472 (18.5%) and 1355 (53.2%) had CVD or cardiovascular risk factors, respectively. Compared with controls (n=718), patients with CVD and cardiovascular risk factors were older and more likely to have had severe COVID-19. Full recovery was significantly lower at 12 months in patients with CVD (adjusted OR (aOR) 0.62, 95% CI 0.43 to 0.89) and cardiovascular risk factors (aOR 0.66, 95% CI 0.50 to 0.86).

CONCLUSION

Patients with CVD or cardiovascular risk factors had a delayed recovery at 12 months following hospitalisation with COVID-19. Targeted interventions to reduce the impact of COVID-19 in patients with cardiovascular disease remain an unmet need.

TRAIL REGISTRATION NUMBER

ISRCTN10980107.

Risks of alopecia areata in long COVID: Binational population-based cohort studies from South Korea and Japan

Previous studies have proposed alopecia areata (AA) as a potential outcome of COVID-19 infection among autoimmune diseases, yet the findings might be inconclusive and difficult to generalize due to limited sample sizes and evidence levels. Thus, we aimed to investigate in detail the long-term risk of AA following SARS-CoV-2 infection based on large, binational, general population-based cohort studies. Our study investigated the long-term AA risk after SARS-CoV-2 infection by analyzing bi-national, claim-based cohorts in South Korea and Japan: a Korean nationwide cohort (K-COV-N cohort; discovery cohort; total n = 10 027 506) and a Japanese claims-based cohort (JMDC cohort; validation cohort; total n = 12 218 680). AA was identified based on the international classification of diseases 10th revision code (L63) requiring at least three claims within 1 year. After exposure-driven propensity score matching, SARS-CoV-2 infection was associated with an increased risk of incident AA (aHR, 1.66; 95% CI, 1.38-1.99). This increased risk was observed and persisted for up to 6 months. A similar pattern was observed in the validation cohort. As modifiable factors, severe COVID-19 increased the risk of AA, whereas receiving two or more doses of the COVID-19 vaccine before infection decreased the risk of AA. Through a bi-national cohort study in South Korea and Japan, SARS-CoV-2 infection was associated with an elevated risk for incident AA in the aspect of long COVID.

Autoimmunity and long COVID in children

Numerous hypotheses regarding the pathogenetic mechanisms of long COVID have been proposed. Immune dysregulation and autoimmunity are among the leading hypotheses. In this article, we present two clinical cases of long COVID. The first case demonstrates the phenotype of long COVID with pain and musculoskeletal symptoms, which is often associated with autoimmunity and mimics systemic connective tissue diseases. In the second case, a high titer of antinuclear antibodies was observed after SARS-CoV-2 infection, but the clinical symptoms were limited to fever and headache. Only a comprehensive evaluation of clinical symptoms and thorough objective examination can confirm or exclude autoimmune diseases after a previous SARS-CoV-2 infection. A systematic search in the PubMed Medline database was carried out for studies focusing on immune dysregulation, autoimmunity, and its association with the clinical phenotype of long COVID. The question of the role of autoimmunity in the development of long COVID and the management approaches are discussed.

Laboratory Findings and Biomarkers in Long COVID: What Do We Know So Far? Insights into Epidemiology, Pathogenesis, Therapeutic Perspectives and Challenges

Long COVID (LC) encompasses a constellation of long-term symptoms experienced by at least 10% of people after the initial SARS-CoV-2 infection, and so far it has affected about 65 million people. The etiology of LC remains unclear; however, many pathophysiological pathways may be involved, including viral persistence; a chronic, low-grade inflammatory response; immune dysregulation and a defective immune response; the reactivation of latent viruses; autoimmunity; persistent endothelial dysfunction and coagulopathy; gut dysbiosis; hormonal and metabolic dysregulation; mitochondrial dysfunction; and autonomic nervous system dysfunction. There are no specific tests for the diagnosis of LC, and clinical features including laboratory findings and biomarkers may not specifically relate to LC. Therefore, it is of paramount importance to develop and validate biomarkers that can be employed for the prediction, diagnosis and prognosis of LC and its therapeutic response, although this effort may be hampered by challenges pertaining to the non-specific nature of the majority of clinical manifestations in the LC spectrum, small sample sizes of relevant studies and other methodological issues. Promising candidate biomarkers that are found in some patients are markers of systemic inflammation, including acute phase proteins, cytokines and chemokines; biomarkers reflecting SARS-CoV-2 persistence, the reactivation of herpesviruses and immune dysregulation; biomarkers of endotheliopathy, coagulation and fibrinolysis; microbiota alterations; diverse proteins and metabolites; hormonal and metabolic biomarkers; and cerebrospinal fluid biomarkers. At present, there are only two reviews summarizing relevant biomarkers; however, they do not cover the entire umbrella of current biomarkers, their link to etiopathogenetic mechanisms or the diagnostic work-up in a comprehensive manner. Herein, we aim to appraise and synopsize the available evidence on the typical laboratory manifestations and candidate biomarkers of LC, their classification based on pathogenetic mechanisms and the main LC symptomatology in the frame of the epidemiological and clinical aspects of the syndrome and furthermore assess limitations and challenges as well as potential implications in candidate therapeutic interventions.

Long COVID: Costs for the German economy and health care and pension system

BACKGROUND

Patients with acute COVID-19 can develop persistent symptoms (long/post COVID-19 syndrome). This study aimed to project the economic, health care, and pension costs due to long/post-COVID-19 syndrome with new onset in Germany in 2021.

METHODS

Using secondary data, economic costs were calculated based on wage rates and the loss of gross value-added. Pension payments were determined based on the incidence, duration, and amount of disability pensions. Health care expenditure was calculated based on rehabilitation expenses.

RESULTS

The analysis estimated a production loss of 3.4 billion euros. The gross value-added loss was calculated to be 5.7 billion euros. The estimated financial burden on the health care and pension systems due to SARS-CoV-2 infection was approximately 1.7 billion euros. Approximately 0.4 percent of employees are projected to be wholly or partially withdrawn from the labor market in the medium term due to long/post-COVID with new onset in 2021.

CONCLUSION

Costs of long/post-COVID-19 syndrome with new onset in 2021 are not negligible for the German economy and health care and pension systems but may still be manageable.