Post-infectious Syndrome Research Articles

Is SARS-CoV-2 the only cause of long-COVID?

Around 10% of adults infected with SARS-CoV-2 that survive a first episode of COVID-19 appear to experience long-term clinical manifestations. The signs and symptoms of this post-acute COVID-19 syndrome (PACS) include fatigue, dyspnea, joint pain, myalgia, chest pain, cough, anosmia, dysgeusia, headache, depression, anxiety, memory loss, concentration difficulties, and insomnia. These sequelae remind the constellation of clinical manifestations previously recognized as myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS). This condition has been described following distinct infectious events, mostly acute viral illnesses. In this way, the pathophysiology of PACS might overlap with mechanisms involved in other post-infectious fatigue syndromes. The risk of PACS is more frequent in women than men. Additional host genetic factors could be involved. There is a dysregulation of multiple body organs and systems, involving the immune system, the coagulation cascade, endocrine organs, autonomic nervous system, microbiota-gut-brain axis, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-thyroid axis, etc. Hypothetically, an abnormal response to certain infectious agents could trigger the development of postinfectious fatigue syndromes.

Systems Thinking, Causal Loop Diagram, and Systems Dynamic in Public Health Challenges: Navigating Long COVID Syndrome and Sense of Smell in LGBTQIA+ Communities

ABSTRACTBackgroundThe coronavirus pandemic has profoundly affected global health, economic stability, and environmental sustainability. Despite these challenges, significant gaps in data remain, particularly in effectively assessing and engaging diverse communities such as color, LGBTQIA+ individuals, and low‐income groups. This shortage of comprehensive research limits our capacity to undertake sensitive studies, specifically in dealing with the complexities of long COVID, which some individuals continue to suffer from after their initial recovery.ObjectiveThis review delves into the ongoing repercussions of long‐term COVID‐19, a postinfectious syndrome marked by neurological symptoms such as cognitive deficits and sensory impairments, which may last well beyond the acute phase of the illness. These symptoms frequently overlap with mental health issues (e.g., anxiety and depression), which can aggravate the socioeconomic challenges faced by vulnerable populations, especially within the LGBTQA+ communities.MethodsTo tackle these complex interactions, we have introduced a novel public health framework: model‐based systems thinking (MBST), which incorporates System Dynamics and causal loop diagrams (CLD).Results and DiscussionThe articles were selected on the basis of their discussion of COVID‐19‐associated anosmia, exploration of olfactory dysfunction alongside neurocognitive disorders, and the challenges experienced in LGBQA+ communities. This approach offers a robust framework for dissecting the intricate ties between socioeconomic factors, health outcomes, and the extended recovery trajectories associated with long‐term COVID‐19, with a particular focus on olfactory dysfunction. We also explore strategies to make our models more accessible to healthcare providers and the LGBTQA+ communities, encouraging its broader adoption.ConclusionLong COVID's impact on public health and marginalized communities highlights the urgent need for adopting systems thinking models. Additionally, this article calls for a concerted effort from all experts to foster multidisciplinary, team‐based research and implement effective support measures for COVID‐19 survivors across all communities, mainly focusing on the scientific, social, and behavioral challenges LGBTQIA+ and low‐income individuals face.

Sleep disorder syndromes of post-acute sequelae of SARS-CoV-2 (PASC) / Long Covid

IntroductionCOVID-19 infection has resulted in a high prevalence of a post-infectious syndrome, known as post-acute sequelae of SARS-CoV-2 (PASC) or “Long COVID”. PASC is a heterogeneous disease with a high prevalence of sleep disturbances, varying from an insomnia disorder to excessive daytime sleepiness. MethodsPatients seen in the Covid Survivorship Program at the Beth Israel Deaconess Medical Center Boston, USA, were screened for sleep disorders as part of a comprehensive multi-system evaluation. Those who screened positive were referred for a comprehensive sleep evaluation in a dedicated COVID-19-Sleep clinic, followed by diagnostic sleep testing and treatment. This report summarizes patients who completed an American Academy of Sleep Medicine (AASM) accredited facility-based diagnostic evaluation. International Classification of Sleep Disorders 3rd Edition-Revised criteria were met for all diagnoses. ResultsIn 42 patients with PASC, five categories of sleep disorder syndromes were observed following a sleep clinic evaluation, including obstructive sleep apnea, chronic insomnia disorder, primary hypersomnia, REM behavior disorder (RBD), and new onset circadian phase delay. Seven patients met criteria for idiopathic hypersomnia, and two had narcolepsy type 2. RBD patients were infected in three different waves; circadian disturbance patients were all infected in the winter wave of 2020/21, and the primary hypersomnolence group occurred during all waves, predominantly the initial wave of 2020. A peculiar form of insomnia was a persistent loss of sleep regularity. ConclusionsSpecific sleep symptoms/syndromes are reported in this select group of patients with PASC/Long Covid. As new onset sleep complaints are prevalent in PASC, we recommend a complete clinical and investigative sleep evaluation for persistent severe sleep symptoms following COVID-19 infection.

Mucosal vaccination in a murine gnotobiotic model of Giardia lamblia infection.

Giardia lamblia is an important protozoan cause of diarrheal disease worldwide, delayed development and cognitive impairment in children in low- and middle-income countries, and protracted post-infectious syndromes in developed regions. G. lamblia resides in the lumen and at the epithelial surface of the proximal small intestine but is not mucosa invasive. The protozoan parasite is genetically diverse with significant genome differences across strains and assemblages. Animal models, particularly murine models, have been instrumental in defining mechanisms of host defense against G. lamblia, but mice cannot be readily infected with most human pathogenic strains. Antibiotic pretreatment can increase susceptibility, suggesting that the normal microbiota plays a role in controlling G. lamblia infection in mice, but the broader implications on susceptibility to diverse strains are not known. Here, we have used gnotobiotic mice to demonstrate that robust intestinal infection can be achieved for a broad set of human-pathogenic strains of the genetic assemblages A and B. Furthermore, gnotobiotic mice were able to eradicate infection with a similar kinetics to conventional mice after trophozoite challenge. Germ-free mice could also be effectively immunized by the mucosal route with a protective antigen, α1-giardin, in a manner dependent on CD4 T cells. These results indicate that the gnotobiotic mouse model is powerful for investigating acquired host defenses in giardiasis, as the mice are broadly susceptible to diverse G. lamblia strains yet display no apparent defects in mucosal immunity needed for controlling and eradicating this lumen-dwelling pathogen.

A Multimodal Ayurveda and Mind-Body Therapeutic Intervention for Chronic Symptoms Attributed to a Postinfectious Syndrome: A Pilot Study.

Objective: Evaluate feasibility and impact of a multimodal integrative therapeutic intervention in patients presenting with chronic symptoms attributed to a postinfectious syndrome. Design: This was a prospective longitudinal single-center pilot study conducted from January 2019 to December 2020. Setting/Location: University of Maryland Lyme Program, Baltimore Maryland. Subjects: Persons presenting for Lyme evaluation for symptoms attributed to Lyme disease. Interventions: Participants attended two 1-h individual instructional sessions consisting of Ayurveda-based dietary intervention and breath-coordinated mind-body practice to be used for home practice. Outcome measures: Standard measures of impact were obtained at baseline, 1, 3, 6, and 12 months using the following validated survey instruments: Perceived Stress Scale (PSS), PROMIS Global Health v1.2 (GH), and PROMIS 29 v2.0 survey. Results: From 216 patients presenting for Lyme evaluation, 19 participants enrolled with 84% completing the study (N = 16). Baseline PROMIS GH scores consisting of general Physical Health (GPH) and general Mental Health (GMH) scores were lower in the study population than in the general U.S. population. PROMIS 29 scores were higher for fatigue, anxiety, and pain than those in the general U.S. population. Over 12-month period, improvement in both the GPH and GMH was 6.09 (confidence interval [95% CI] = 2.71-9.46; p < 0.001) and 4.65 (95% CI = 1.50-7.80; p = 0.004), respectively. PROMIS 29 scores showed the greatest improvement in fatigue at -7.91 (95% CI = -12.34 to -3.48; p < 0.001), pain interference -5.08 (95% CI = -9.20 to -0.96; p = 0.016), and ability to participate in social roles and activities 7.48 (95% CI = 3.21-11.75; p = 0.001) and least with depression -1.82 (95% CI = -4.74 to 1.10; p = 0.223). Employment status had significant effects on almost all outcome scores. Postinfectious state was associated with improvement in anxiety and PSS scores. Conclusions: A multimodal Ayurvedic and breath-coordinated mind-body therapeutic intervention is feasible and a potential nonpharmacologic therapeutic option for persons presenting with pain, stress, fatigue, physical dysfunction, and sleep disturbance attributed to a postinfectious syndrome. Further research is needed to determine efficacy in this population and in other groups with similar symptom complexes due to postinfectious syndromes.

Long COVID and post-acute sequelae of SARS-CoV-2 pathogenesis and treatment: A Keystone Symposia report.

In 2023, the Keystone Symposia held the first international scientific conference convening research leaders investigating the pathology of post-acute sequelae of COVID-19 (PASC) or Long COVID, a growing and urgent public health priority. In this report, we present insights from the talks and workshops presented during this meeting and highlight key themes regarding what researchers have discovered regarding the underlying biology of PASC and directions toward future treatment. Several themes have emerged in the biology, with inflammation and other immune alterations being the most common focus, potentially related to viral persistence, latent virus reactivation, and/or tissue damage and dysfunction, especially of the endothelium, nervous system, and mitochondria. In order to develop safe and effective treatments for people with PASC, critical next steps should focus on the replication of major findings regarding potential mechanisms, disentangling pathogenic mechanisms from downstream effects, development of cellular and animal models, mechanism-focused randomized, placebo-controlled trials, and closer collaboration between people with lived experience, scientists, and other stakeholders. Ultimately, by learning from other post-infectious syndromes, the knowledge gained may help not only those with PASC/Long COVID, but also those with other post-infectious syndromes.

De novo design of potential peptide analogs against the main protease of Omicron variant using in silico studies.

SARS-CoV-2 and its variants are crossing the immunity barrier induced through vaccination. Recent Omicron sub-variants are highly transmissible and have a low mortality rate. Despite the low severity of Omicron variants, these new variants are known to cause acute post-infectious syndromes. Nowadays, novel strategies to develop new potential inhibitors for SARS-CoV-2 and other Omicron variants have gained prominence. For viral replication and survival the main protease of SARS-CoV-2 plays a vital role. Peptide-like inhibitors that mimic the substrate peptide have already proved to be effective in inhibiting the Mpro of SARS-CoV-2 variants. Our systematic canonical amino acid point mutation analysis on the native peptide has revealed various ways to improve the native peptide of the main protease. Multi mutation analysis has led us to identify and design potent peptide-analog inhibitors that act against the Mpro of the Omicron sub-variants. Our in-depth analysis of all-atom molecular dynamics studies has paved the way to characterize the atomistic behavior of Mpro in Omicron variants. Our goal is to develop potent peptide-analogs that could be therapeutically effective against Omicron and its sub-variants.

Nutritional Intervention Based on Novel Coronavirus Postinfection Syndrome

When the novel coronavirus pneumonia (COVID-19) pandemic broke out, the focus of global efforts was to curb the spread of the virus to avoid infection. The COVID-19 epidemic has not only caused infection on people, but also adverse effects. Though the spread of COVID-19 has been well controlled nowadays, its potential sustained impact on the human body cannot be ignored, and its overall health needs continued attention. The World Health Organization (WHO) has uniformly named various symptoms that persist after COVID-19 infection as novel coronavirus post infection syndrome (PCS). PCS has various impacts on patients, such as respiratory dysfunction, muscle loss, intestinal microbiota disorder, physical dysfunction and mental health impact. Proper nutritional assessment is one of the key links in treating or preventing the progression of PCS patients. Additionally, individualized nutritional advice has been shown to be a successful method of helping patients recover. To learn more about the function of nutrients and their supplementation in PCS and the clinical data supporting those claims, see this review, in order to provide practical guidance and suggestions for nutritionists and tailor personalized dietary interventions for PCS patients.

Dengue virus infection and neurological manifestations: an update.

Dengue virus is a flavivirus transmitted by the mosquitoes, Aedes aegypti and Aedes albopictus. Dengue infection by all four serotypes (DEN 1 to 4) is endemic globally in regions with tropical and subtropical climates, with an estimated 100-400 million infections annually. Among those hospitalized, the mortality is about 1%. Neurological involvement has been reported to be about 5%. The spectrum of neurological manifestations spans both the peripheral and central nervous systems. These manifestations could possibly be categorized into those directly related to dengue infection, i.e. acute and chronic encephalitis, indirect complications leading to dengue encephalopathy, and post-infectious syndrome due to immune-mediated reactions, and manifestations with uncertain mechanisms, such as acute transverse myelitis, acute cerebellitis and myositis. The rising trend in global dengue incidence calls for attention to a more explicit definition of each neurological manifestation for more accurate epidemiological data. The actual global burden of dengue infection with neurological manifestation is essential for future planning and execution of strategies, especially in the development of effective antivirals and vaccines against the dengue virus. In this article, we discuss the recent findings of different spectrums of neurological manifestations in dengue infection and provide an update on antiviral and vaccine development and their challenges.

Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles

The SARS-CoV-2 pandemic not only resulted in millions of acute infections worldwide, but also in many cases of post-infectious syndromes, colloquially referred to as “long COVID”. Due to the heterogeneous nature of symptoms and scarcity of available tissue samples, little is known about the underlying mechanisms. We present an in-depth analysis of skeletal muscle biopsies obtained from eleven patients suffering from enduring fatigue and post-exertional malaise after an infection with SARS-CoV-2. Compared to two independent historical control cohorts, patients with post-COVID exertion intolerance had fewer capillaries, thicker capillary basement membranes and increased numbers of CD169+ macrophages. SARS-CoV-2 RNA could not be detected in the muscle tissues. In addition, complement system related proteins were more abundant in the serum of patients with PCS, matching observations on the transcriptomic level in the muscle tissue. We hypothesize that the initial viral infection may have caused immune-mediated structural changes of the microvasculature, potentially explaining the exercise-dependent fatigue and muscle pain.Graphical

Long COVID in Icelandic Children: A Matched Cohort Study of Nonspecific Symptoms Following SARS-CoV-2 Infection.

Pediatric severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections are usually mild and the mortality rates are low, but concerns have been raised about long-term symptoms that may resemble other postinfectious syndromes. Studies with robust control groups and high response rates have been few. We obtained identifiers for all 837 Icelandic children diagnosed with SARS-CoV-2 by PCR between March 2020 and June 2021 and contacted them by telephone. We asked about 10 physical and mental symptoms being present at least twice weekly for at least 2 months. Participants who reported symptoms were contacted again a year later. For each subject who completed the questionnaire, an age- and sex-matched comparator without SARS-CoV-2 infection was asked to complete the same questionnaire, and the risk difference was calculated. Responses from 643 cases and 602 comparators were analyzed. Children who had been infected with SARS-CoV-2 were more likely to report one or more symptoms, except for anxiety/depression and sleep disturbances. Fatigue and loss of concentration were evidently more common in cases among teenagers (risk difference: 15%; 95% CI: 7-22% and 15%; 95% CI: 7-23%, respectively). At the second follow-up, close to a third of Long COVID cases had resolved but some participants had developed new persistent symptoms. Symptoms of Long COVID in children are common and impact their quality of life. The importance of further unraveling the pathophysiology of acute and long-term symptoms following SARS-CoV-2 infection in children is vital as well as potential preventive measures.

Синдром мальабсорбції після перенесеного гастроентериту в дітей, оптимізація терапії

The period of convalescence after gastroenteritis in children in modern circumstances is often complicated by the development of post-infectious malabsorption syndrome, in the pathogenesis of which the development of bacterial overgrowth syndrome (BOS) is important. At present, the issue of treatment of BOS in children has not been finally resolved. The use of modern enterosorbents can be considered a good alternative to antibacterial therapy of BOS. Purpose - to evaluate the effectiveness of the inclusion of highly dispersed silicon dioxide in the complex therapy of malabsorption syndrome after gastroenteritis in children. Materials and methods. 30 children aged from 3 to 12 years with malabsorption syndrome after gastroenteritis during the last 6 months were under observation. Patients on the background of standard treatment were prescribed highly dispersed silicon dioxide for 3-5 days. In dynamics, subjective complaints of patients and/or their parents were assessed, clinical symptoms and results of coprological and bacteriological examination of feces were evaluated. Results. While including highly dispersed silicon dioxide into the treatment, in the vast majority of patients (according to individual indicators, 75-85%), a rapid normalization of the frequency and consistency of stools, a decrease in the frequency and severity of flatulence, improvement of digestion and assimilation of nutrients according to the indicators of a coprological study, which had a positive effect on the general condition, were noted. The results of the bacteriological examination of feces in dynamics showed a significant decrease in the frequency of detection and the number of opportunistic bacteria, fungal flora and tendency to increase the number of representatives of the indigenous microflora. Conclusions. The results of the work make it possible to recommend the inclusion of enterosorption with the usage of highly dispersed silicon dioxide in the complex of restorative therapy in children with malabsorption syndrome after gastroenteritis. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the institution mentioned in the work. The informed consent of the children’s parents was obtained for the conducting the studies. No conflict of interests was declared by the authors.

Positional shunt assist for slit ventricle syndrome.

Hydrocephalus is one of the most common pathologies in pediatric neurosurgery. One of the causes of recurring events of headaches among shunted children is "slit ventricle syndrome" (SVS). Several potential treatments have been proposed, yet SVS often represents a treatment challenge. The goal of the current series is to present our experience with adding a positional shunt-assist (SA) (Miethke, Aesculap) for the treatment of SVS. Clinical data was retrospectively collected from all consecutive children with SVS that were treated with SA (Miethke, Aesculap) at our center. Surgical and clinical outcomes as expressed by hospital visits, or need for additional surgery, were evaluated. Nine cases were included. Hydrocephalus etiology included IVH (6), postinfectious (1), and congenital syndromes (2). Average age at first shunt was 4months. Primary shunt type was differential-pressure-valve in all. Average age at SVS onset was 4years. Average age at SA placement was 5.5years. There were no perioperative complications besides a single stich abscess. A 6-month follow-up period after SA was compared to a 6-month period prior to the SA: average hospital visits decreased from 2.4 to 0.6 per patient (p < 0.0002). 4/9 patients needed an LP or shunt revision before the SA surgery, while no procedure was indicated during the immediate 6-month follow-up. At the last follow-up, there was a significant reduction in the rate of ER visits compared to prior to surgery; however, the number of neurosurgical procedures did not significantly differ. Using a SA for SVS was associated with a short-term improvement of symptoms in the majority of cases, reduction in hospital visits, and reduced need for SVS-related procedures.

Long-term symptom severity and clinical biomarkers in post-COVID-19/chronic fatigue syndrome: results from a prospective observational cohort

Post-COVID-19 syndrome (PCS) is characterised by a wide range of symptoms, primarily fatigue and exertion intolerance. While disease courses in the early months post-infection have been well-described, the long-term health consequences for patients with PCS with disabling fatigue remain unclear. In this prospective observational cohort study, we evaluated symptom severity and various biomarkers, including hand grip strength (HGS), cardiovascular function, and laboratory parameters, in 106 patients with PCS with moderate to severe fatigue and exertion intolerance at three time points after infection (3-8, 9-16, and 17-20 months). The study was conducted at the Charité's Fatigue Centre and the Charité's outpatient clinic for neuroimmunology at Berlin, Germany from July 16, 2020, to February 18, 2022. A subset of patients (PCS-ME/CFS) met the diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome according to the Canadian Consensus Criteria (CCC). The aim was to determine differences in the disease course between the two patient groups (i.e., PCS vs PCS-ME/CFS) and identify correlating biomarkers. Patients with PCS-ME/CFS reported persistently high severity of most symptoms up to 20 months after infection, while patients with PCS showed overall health improvement. Although fatigue and post-exertional malaise (PEM), hallmarks of post-infectious fatigue syndromes, were still evident in both groups, they remained more pronounced in PCS-ME/CFS. Inflammatory biomarkers decreased in both groups, but not antinuclear antibodies. Lower HGS at onset correlated with symptom persistence, particularly in patients with PCS-ME/CFS. Our findings suggest that PCS can persist beyond 20 months post-infection and encompass the full scope of post-infectious ME/CFS as defined by the CCC. Sub-classifying patients with PCS based on the CCC can assist in the management and monitoring of patients with PCS-ME/CFS due to their persistently higher symptom severity. C. S. was supported by a grant from the Weidenhammer-Zoebele Foundation. F. K. was supported by the Volkswagen Foundation.

Icosapent ethyl (VASCEPA®) as treatment for post-acute sequelae of SARS CoV-2 (PASC) vaccine induced injury and infection.

As the COVID-19 pandemic continues, a prolonged post-infectious syndrome or "long COVID" has been reported. This is a multi-organ post viral syndrome that persists well after infection. Currently, there is no available treatment. Emerging evidence credits this "long COVID" syndrome to ongoing inflammatory response following resolution of symptoms during infection. An omega-three fatty acid derivative used in the treatment of hypertriglyceridemia, Icosapent Ethyl (IPE, VASCEPA®/Epadel®), was previously shown to reduce cardiovascular risk, likely via immunomodulatory effects. This study aims to evaluate the effectiveness of Icosapent Ethyl. Following previous publications in treatment of severe acute COVID-19, we analyze two case studies of adults treated with Icosapent Ethyl. After experiencing the symptoms of Long Covid, both individuals analyzed across two case studies experiences a resolution of symptoms after treatment with Icosapent Ethyl. After review and analysis we conclude that Icosapent Ethyl may have been a determining factor in Long COVID symptom resolution and should be studied further.

Mechanisms and Severity of Exercise Intolerance Following COVID-19 and Similar Viral Infections: A Comparative Review.

Approximately 19% of the population is suffering from "Long COVID", also known as post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC), which often results in exercise intolerance. As COVID infections continue to be common, studying the long-term consequences of coronavirus disease (COVID) on physical function has become increasingly important. This narrative review will aim to summarize the current literature surrounding exercise intolerance following COVID infection in terms of mechanism, current management approaches, and comparison with similar conditionsand will aim to define limitations in the current literature. Multiple organ systems have been implicated in the onset of long-lasting exercise intolerance post-COVID, including cardiac impairment, endothelial dysfunction, decreased VO2 max and oxygen extraction, deconditioning due to bed rest, and fatigue. Treatment modalities for severe COVID have also been shown to cause myopathy and/or worsen deconditioning. Besides COVID-specific pathophysiology, general febrile illness as commonly experienced during infection will cause hypermetabolic muscle catabolism, impaired cooling, and dehydration, which acutely cause exercise intolerance. The mechanisms of exercise intolerance seen with PASC also appear similar to post-infectious fatigue syndrome and infectious mononucleosis. However, the severity and duration of the exercise intolerance seen with PASC is greater than that of any of the isolated mechanisms described above and thus is likely a combination of the proposed mechanisms. Physicians should consider post-infectious fatigue syndrome (PIFS), especially if fatigue persists after six months following COVID recovery. It is important for physicians, patients, and social systems to anticipate exercise intolerance lasting for weeks to months in patients with long COVID. These findings underscore the importance of long-term management of patients with COVID and the need for ongoing research to identify effective treatments for exercise intolerance in this population. By recognizing and addressing exercise intolerance in patients with long COVID, clinicians can provide proper supportive interventions, such as exercise programs, physical therapy, and mental health counseling, to improve patient outcomes.

Clinical improvement of Long-COVID is associated with reduction in autoantibodies, lipids, and inflammation following therapeutic apheresis

In the aftermath of the COVID-19 pandemic, we are witnessing an unprecedented wave of post-infectious complications. Most prominently, millions of patients with Long-Covid complain about chronic fatigue and severe post-exertional malaise. Therapeutic apheresis has been suggested as an efficient treatment option for alleviating and mitigating symptoms in this desperate group of patients. However, little is known about the mechanisms and biomarkers correlating with treatment outcomes. Here, we have analyzed in different cohorts of Long-Covid patients specific biomarkers before and after therapeutic apheresis. In patients that reported a significant improvement following two cycles of therapeutic apheresis, there was a significant reduction in neurotransmitter autoantibodies, lipids, and inflammatory markers. Furthermore, we observed a 70% reduction in fibrinogen, and following apheresis, erythrocyte rouleaux formation and fibrin fibers largely disappeared as demonstrated by dark field microscopy. This is the first study demonstrating a pattern of specific biomarkers with clinical symptoms in this patient group. It may therefore form the basis for a more objective monitoring and a clinical score for the treatment of Long-Covid and other postinfectious syndromes.

Immune system perturbations in patients with severe long COVID

Abstract SARS-CoV-2 infections have different outcomes ranging from mild to severe acute infection as well as post-infectious multi-system inflammatory syndromes (MIS-C/A). Post-acute sequelae of COVID-19 (PASC) or long COVID is another outcome, which is poorly understood and range from mild to very severe persistent organ dysfunction and damages. To maximize our chances of identifying underlying mechanisms of long COVID we focus on the most severe cases with objective measures of disease such as lung damages, microvascular and autonomic nerve dysfunction. We are testing the following hypotheses that I) long COVID is a super-antigen mediated disease, II) an autoimmune condition driven by pathogenic autoantibodies, and/or III) a disease caused by viral persistence. A cohort of over 100 long COVID patients, 24 recovered long COVID patients as well as 9 COVID convalescent controls have been recruited thus far and blood samples analyzed for plasma proteome (Olink assays), immune cell composition and phenotypes (mass cytometry), T-cell repertoire (scTCR-seq), innate cell activation (circulating nucleosomes), and auto-antibody analyses (Luminex arrays) in order to understand immune perturbations in severe long COVID patients. Unlike children with hyperinflammatory MIS-C, we have not found any evidence of superantigen-mediated T-cell activation in long COVID, but instead substantial clonal expansion of memory T cell clones with effector memory states and shared clonality across patients. Additionally, cytokine perturbations such as elevated levels of IL8 and elevated levels of circulating nucleosomes indicate persistent activation of neutrophils in severe long COVID.

Multiplatform analyses reveal distinct drivers of systemic pathogenesis in adult versus pediatric severe acute COVID-19

The pathogenesis of multi-organ dysfunction associated with severe acute SARS-CoV-2 infection remains poorly understood. Endothelial damage and microvascular thrombosis have been identified as drivers of COVID-19 severity, yet the mechanisms underlying these processes remain elusive. Here we show alterations in fluid shear stress-responsive pathways in critically ill COVID-19 adults as compared to non-COVID critically ill adults using a multiomics approach. Mechanistic in-vitro studies, using microvasculature-on-chip devices, reveal that plasma from critically ill COVID-19 adults induces fibrinogen-dependent red blood cell aggregation that mechanically damages the microvascular glycocalyx. This mechanism appears unique to COVID-19, as plasma from non-COVID sepsis patients demonstrates greater red blood cell membrane stiffness but induces less significant alterations in overall blood rheology. Multiomics analyses in pediatric patients with acute COVID-19 or the post-infectious multi-inflammatory syndrome in children (MIS-C) demonstrate little overlap in plasma cytokine and metabolite changes compared to adult COVID-19 patients. Instead, pediatric acute COVID-19 and MIS-C patients show alterations strongly associated with cytokine upregulation. These findings link high fibrinogen and red blood cell aggregation with endotheliopathy in adult COVID-19 patients and highlight differences in the key mediators of pathogenesis between adult and pediatric populations.

Severe COVID-19 versus multisystem inflammatory syndrome: comparing two critical outcomes of SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with diverse host response immunodynamics and variable inflammatory manifestations. Several immune-modulating risk factors can contribute to a more severe coronavirus disease 2019 (COVID-19) course with increased morbidity and mortality. The comparatively rare post-infectious multisystem inflammatory syndrome (MIS) can develop in formerly healthy individuals, with accelerated progression to life-threatening illness. A common trajectory of immune dysregulation forms a continuum of the COVID-19 spectrum and MIS; however, severity of COVID-19 or the development of MIS is dependent on distinct aetiological factors that produce variable host inflammatory responses to infection with different spatiotemporal manifestations, a comprehensive understanding of which is necessary to set better targeted therapeutic and preventative strategies for both.