Serum Metabolic Profile in Patients With Long-Covid (PASC) Syndrome: Clinical Implications

What Role Does Microthrombosis Play in Long COVID?

Soon after the outbreak of coronavirus disease 2019 (COVID-19), unexplained sustained fatigue, cognitive disturbance, and muscle ache/weakness were reported in patients who had recovered from acute COVID-19 infection. This abnormal condition has been recognized as "long COVID (postacute sequelae of COVID-19 [PASC])" with a prevalence estimated to be from 10 to 20% of convalescent patients. Although the pathophysiology of PASC has been studied, the exact mechanism remains obscure. Microclots in circulation can represent one of the possible causes of PASC. Although hypercoagulability and thrombosis are critical mechanisms of acute COVID-19, recent studies have reported that thromboinflammation continues in some patients, even after the virus has cleared. Viral spike proteins and RNA can be detected months after patients have recovered, findings that may be responsible for persistent thromboinflammation and the development of microclots. Despite this theory, long-term results of anticoagulation, antiplatelet therapy, and vascular endothelial protection are inconsistent, and could not always show beneficial treatment effects. In summary, PASC reflects a heterogeneous condition, and microclots cannot explain all the presenting symptoms. After clarification of the pathomechanisms of each symptom, a symptom- or biomarker-based stratified approach should be considered for future studies.

Long-COVID is Associated with Impaired Red Blood Cell Function

COVID-19 disease, caused by the severe acute respiratory syndrome virus 2 (SARS-CoV-2), induces a broad spectrum of clinical symptoms ranging from asymptomatic cases to fatal outcomes. About 10-35% of all COVID-19 patients, even those with mild COVID-19 symptoms, continue to show symptoms, i. e., fatigue, shortness of breath, cough, and cognitive dysfunction, after initial recovery. Previously, we and others identified red blood cell precursors as a direct target of SARS-CoV-2 and suggested that SARS-CoV-2 induces dysregulation in hemoglobin- and iron-metabolism contributing to the severe systemic course of COVID-19. Here, we put particular emphasis on differences in parameters of clinical blood gas analysis and hematological parameters of more than 20 healthy and Long-COVID patients, respectively. Long-COVID patients showed impaired oxygen binding to hemoglobin with concomitant increase in carbon monoxide binding. Hand in hand with decreased plasma iron concentration and transferrin saturation, mean corpuscular hemoglobin was elevated in Long-COVID patients compared to healthy donors suggesting a potential compensatory mechanism. Although blood pH was within the physiological range in both groups, base excess- and bicarbonate values were significantly lower in Long-COVID patients. Furthermore, Long-COVID patients displayed reduced lymphocyte levels. The clinical relevance of these findings, e. g., as a cause of chronic immunodeficiency, remains to be investigated in future studies. In conclusion, our data suggest impaired erythrocyte functionality in Long-COVID patients, leading to diminished oxygen supply. This in turn could be an explanation for the CFS, dyspnea and anemia. Further investigations are necessary to identify the underlying pathomechanisms.

COVID-19 and Long-COVID Thrombosis: From Clinical and Basic Science to Therapeutics

Coronavirus infectious disease-19 (COVID-19) is a pandemic characterized by serious lung disease and thrombotic events in the venous and circulation trees, which represent a harmful clinical sign of poor outcome. Thrombotic events are more frequent in patients with severe disease requiring intensive care units and are associated with platelet and clotting activation. However, after resolution of acute infection, patients may still have clinical sequelae, the so-called long-COVID-19, including thrombotic events again in the venous and arterial circulation. The mechanisms accounting for thrombosis in acute and long COVID-19 have not been fully clarified; interactions of COVID-19 with angiotensin converting enzyme 2 or toll-like receptor family or infection-induced cytokine storm have been suggested to be implicated in endothelial cells, leucocytes, and platelets to elicit clotting activation in acute as well in chronic phase of the disease. In acute COVID-19, prophylactic or full doses of anticoagulants exert beneficial effects even if the dosage choice is still under investigation; however, a residual risk still remains suggesting a need for a more appropriate therapeutic approach. In long COVID-19 preliminary data provided useful information in terms of antiplatelet treatment but definition of candidates for thrombotic prophylaxis is still undefined.

Bilateral Avascular Necrosis of the Femoral Heads After COVID-19 Infection without Steroid Treatment

BACKGROUND

Avascular necrosis (AVN) is a potentially serious multifactorial disease. In COVID-19 patients, AVN of many bones has been reported. Usually, the condition is linked to steroid therapy. In this case report, we describe our experience with bilateral AVN of femoral heads in an elderly patient months after being cured of COVID-19 infection without the use of steroids.

CASE PRESENTATION

A 68-year-old male was referred to the outpatient clinic of the rheumatology and rehabilitation department for progressive bilateral hip pain starting on the left side 5 months ago. An extensive review of the patient's medical history identified documented COVID-19 infection that required hospitalization 9 months before presentation. Multiplanar MRI with fat suppression of both hips showed ill-defined areas of abnormal signal intensity affecting the left femoral head, neck and intertrochanteric regions with associated subchondral fissuring and mild joint effusion. A similar smaller area was also seen affecting the postero-superior aspect of the right femoral head.

CONCLUSION

AVN in COVID-19 patients can be encountered even in the absence of steroid therapy.

Low growth hormone secretion associated with post-acute sequelae SARS-CoV-2 infection (PASC) neurologic symptoms: A case-control pilot study

OBJECTIVE

To determine if patients that develop lingering neurologic symptoms of fatigue and "brain fog" after initial recovery from coronavirus disease 2019 (COVID-19) have persistent low growth hormone (GH) secretion as seen in other conditions with similar symptom etiology.

DESIGN

In this case-control observational pilot study, patients reporting lingering neurologic post-acute sequelae of SARS-CoV-2 (PASC, n = 10) symptoms at least 6 months after initial infection were compared to patients that recovered from COVID-19 without lingering symptoms (non-PASC, n = 13). We compared basic blood chemistry and select metabolites, lipids, hormones, inflammatory markers, and vitamins between groups. PASC and non-PASC subjects were tested for neurocognition and GH secretion, and given questionnaires to assess symptom severity. PASC subjects were also tested for glucose tolerance and adrenal function.

RESULTS

PASC subjects reported significantly worse fatigue, sleep quality, depression, quality of life, and gastrointestinal discomfort compared to non-PASC. Although PASC subjects self-reported poor mental resilience, cognitive testing did not reveal significant differences between groups. Neurologic PASC symptoms were not linked to inflammatory markers or adrenal insufficiency, but were associated with reduced growth hormone secretion.

CONCLUSIONS

Neurologic PASC symptoms are associated with gastrointestinal discomfort and persistent disruption of GH secretion following recovery from acute COVID-19. (www.

CLINICALTRIALS

gov; NCT04860869).

Beyond the Acute Phase: Long-Term Impact of COVID-19 on Functional Capacity and Prothrombotic Risk-A Pilot Study

Background and Objectives: Assessment of the prothrombotic, proinflammatory, and functional status of a cohort of COVID-19 patients at least two years after the acute infection to identify parameters with potential therapeutic and prognostic value. Materials and Methods: We conducted a retrospective, descriptive study that included 117 consecutive patients admitted to Iasi Pulmonary Rehabilitation Clinic for reassessment and a rehabilitation program at least two years after a COVID-19 infection. The cohort was divided into two groups based on the presence (n = 49) or absence (n = 68) of pulmonary fibrosis, documented through high-resolution computer tomography. Results: The cohort comprises 117 patients, 69.23% females, with a mean age of 65.74 ± 10.19 years and abnormal body mass index (31.42 ± 5.71 kg/m2). Patients with pulmonary fibrosis have significantly higher levels of C-reactive protein (CRP) (p < 0.05), WBC (7.45 ± 7.86/mm3 vs. 9.18 ± 17.24/mm3, p = 0.053), neutrophils (4.68 ± 7.88/mm3 vs. 9.07 ± 17.44/mm3, p < 0.05), mean platelet volume (MPV) (7.22 ± 0.93 vs. 10.25 ± 0.86 fL, p < 0.05), lactate dehydrogenase (p < 0.05), and D-dimers (p < 0.05), but not ferritin (p = 0.470), reflecting the chronic proinflammatory and prothrombotic status. Additionally, patients with associated pulmonary fibrosis had a higher mean heart rate (p < 0.05) and corrected QT interval (p < 0.05). D-dimers were strongly and negatively correlated with diffusion capacity corrected for hemoglobin (DLCO corr), and ROC analysis showed that the persistence of high D-dimers values is a predictor for low DLCO values (ROC analysis: area under the curve of 0.772, p < 0.001). The results of pulmonary function tests (spirometry, body plethysmography) and the 6-minute walk test demonstrated no significant difference between groups, without notable impairment within either group. Conclusions: Patients with COVID-19-related pulmonary fibrosis have a persistent long-term proinflammatory, prothrombotic status, despite the functional recovery. The persistence of elevated D-dimer levels could emerge as a predictive factor associated with impaired DLCO.

Incidence of type 2 diabetes before and during the COVID-19 pandemic in Naples, Italy: a longitudinal cohort study

Background

The association of COVID-19 with the development of new-onset diabetes has been recently investigated by several groups, yielding controversial results. Population studies currently available in the literature are mostly focused on type 1 diabetes (T1D), comparing patients with a SARS-CoV-2 positive test to individuals without COVID-19, especially in paediatric populations. In this study, we sought to determine the incidence of type 2 diabetes (T2D) before and during the COVID-19 pandemic.

Methods

In this longitudinal cohort study, we analysed a cohort followed up over a 6-year period using an Interrupted Time Series approach, i.e. 3-years before and 3-years during the COVID-19 pandemic. We analysed data obtained from >200,000 adults in Naples (Italy) from January 1st 2017 to December 31st 2022. In this manner, we had the opportunity to compare the incidence of newly diagnosed T2D before (2017-2019) and during (2020-2022) the COVID-19 pandemic. The key inclusion criteria were age >18-year-old and data availability for the period of observation; patients with a diagnosis of diabetes obtained before 2017 were excluded. The main outcome of the study was the new diagnosis of T2D, as defined by the International Classification of Diseases 10 (ICD-X), including prescription of antidiabetic therapies for more than 30 days.

Findings

A total of 234,956 subjects were followed-up for at least 3-years before or 3-years during the COVID-19 pandemic and were included in the study; among these, 216,498 were analysed in the pre-pandemic years and 216,422 in the pandemic years. The incidence rate of T2D was 4.85 (95% CI, 4.68-5.02) per 1000 person-years in the period 2017-2019, vs 12.21 (95% CI, 11.94-12.48) per 1000 person-years in 2020-2022, with an increase of about twice and a half. Moreover, the doubling time of the number of new diagnoses of T2D estimated by unadjusted Poisson model was 97.12 (95% CI, 40.51-153.75) months in the prepandemic period vs 23.13 (95% CI, 16.02-41.59) months during the COVID-19 pandemic. Interestingly, these findings were also confirmed when examining patients with prediabetes.

Interpretation

Our data from this 6-year study on more than 200,000 adult participants indicate that the incidence of T2D was significantly higher during the pandemic compared to the pre-COVID-19 phase. As a consequence, the epidemiology of the disease may change in terms of rates of outcomes as well as public health costs. COVID-19 survivors, especially patients with prediabetes, may require specific clinical programs to prevent T2D.

Funding

The US National Institutes of Health (NIH: NIDDK, NHLBI, NCATS), Diabetes Action Research and Education Foundation, Weill-Caulier and Hirschl Trusts.

Serotonin reduction in post-acute sequelae of viral infection

Post-acute sequelae of COVID-19 (PASC, "Long COVID") pose a significant global health challenge. The pathophysiology is unknown, and no effective treatments have been found to date. Several hypotheses have been formulated to explain the etiology of PASC, including viral persistence, chronic inflammation, hypercoagulability, and autonomic dysfunction. Here, we propose a mechanism that links all four hypotheses in a single pathway and provides actionable insights for therapeutic interventions. We find that PASC are associated with serotonin reduction. Viral infection and type I interferon-driven inflammation reduce serotonin through three mechanisms: diminished intestinal absorption of the serotonin precursor tryptophan; platelet hyperactivation and thrombocytopenia, which impacts serotonin storage; and enhanced MAO-mediated serotonin turnover. Peripheral serotonin reduction, in turn, impedes the activity of the vagus nerve and thereby impairs hippocampal responses and memory. These findings provide a possible explanation for neurocognitive symptoms associated with viral persistence in Long COVID, which may extend to other post-viral syndromes.

Neurologic sequelae of COVID-19 are determined by immunologic imprinting from previous coronaviruses

Coronavirus disease 2019 (COVID-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health emergency. Although SARS-CoV-2 is primarily a respiratory pathogen, extra-respiratory organs, including the CNS, can also be affected. Neurologic symptoms have been observed not only during acute SARS-CoV-2 infection, but also at distance from respiratory disease, also known as long-COVID or neurological post-acute sequelae of COVID-19 (neuroPASC). The pathogenesis of neuroPASC is not well understood, but hypotheses include SARS-CoV-2-induced immune dysfunctions, hormonal dysregulations and persistence of SARS-CoV-2 reservoirs. In this prospective cohort study, we used a high throughput systems serology approach to dissect the humoral response to SARS-CoV-2 (and other common coronaviruses: 229E, HKU1, NL63 and OC43) in the serum and CSF from 112 infected individuals who developed (n = 18) or did not develop (n = 94) neuroPASC. Unique SARS-CoV-2 humoral profiles were observed in the CSF of neuroPASC compared with serum responses. All antibody isotypes (IgG, IgM, IgA) and subclasses (IgA1-2, IgG1-4) were detected in serum, whereas CSF was characterized by focused IgG1 (and absence of IgM). These data argue in favour of compartmentalized brain-specific responses against SARS-CoV-2 through selective transfer of antibodies from the serum to the CSF across the blood-brain barrier, rather than intrathecal synthesis, where more diversity in antibody classes/subclasses would be expected. Compared to individuals who did not develop post-acute complications following infection, individuals with neuroPASC had similar demographic features (median age 65 versus 66.5 years, respectively, P = 0.55; females 33% versus 44%, P = 0.52) but exhibited attenuated systemic antibody responses against SARS-CoV-2, characterized by decreased capacity to activate antibody-dependent complement deposition (ADCD), NK cell activation (ADNKA) and to bind Fcγ receptors. However, surprisingly, neuroPASC individuals showed significantly expanded antibody responses to other common coronaviruses, including 229E, HKU1, NL63 and OC43. This biased humoral activation across coronaviruses was particularly enriched in neuroPASC individuals with poor outcome, suggesting an 'original antigenic sin' (or immunologic imprinting), where pre-existing immune responses against related viruses shape the response to the current infection, as a key prognostic marker of neuroPASC disease. Overall, these findings point to a pathogenic role for compromised anti-SARS-CoV-2 responses in the CSF, likely resulting in incomplete virus clearance from the brain and persistent neuroinflammation, in the development of post-acute neurologic complications of SARS-CoV-2 infection.

Pentameric C-reactive protein is a better prognostic biomarker and remains elevated for longer than monomeric CRP in hospitalized patients with COVID-19

The differing roles of the pentameric (p) and monomeric (m) C-reactive protein (CRP) isoforms in viral diseases are not fully understood, which was apparent during the COVID-19 pandemic regarding the clinical course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Herein, we investigated the predictive value of the pCRP and mCRP isoforms for COVID-19 severity in hospitalized patients and evaluated how the levels of the protein isoforms changed over time during and after acute illness. This study utilized samples from a well-characterized cohort of Swedish patients with SARS-CoV-2 infection, the majority of whom had known risk factors for severe COVID-19 and required hospitalization. The levels of pCRP were significantly raised in patients with severe COVID-19 and in contrast to mCRP the levels were significantly associated with disease severity. Additionally, the pCRP levels remained elevated for at least six weeks post inclusion, which was longer compared to the two weeks for mCRP. Our data indicates a low level of inflammation lasting for at least six weeks following COVID-19, which might indicate that the disease has an adverse effect on the immune system even after the viral infection is resolved. It is also clear that the current standard method of testing pCRP levels upon hospitalization is a useful marker for predicting disease severity and mCRP testing would not add any clinical relevance for patients with COVID-19.

Cardiovascular autonomic dysfunction in "Long COVID": pathophysiology, heart rate variability, and inflammatory markers

Long COVID is characterized by persistent signs and symptoms that continue or develop for more than 4 weeks after acute COVID-19 infection. Patients with Long COVID experience a cardiovascular autonomic imbalance known as dysautonomia. However, the underlying autonomic pathophysiological mechanisms behind this remain unclear. Current hypotheses include neurotropism, cytokine storms, and inflammatory persistence. Certain immunological factors indicate autoimmune dysfunction, which can be used to identify patients at a higher risk of Long COVID. Heart rate variability can indicate autonomic imbalances in individuals suffering from Long COVID, and measurement is a non-invasive and low-cost method for assessing cardiovascular autonomic modulation. Additionally, biochemical inflammatory markers are used for diagnosing and monitoring Long COVID. These inflammatory markers can be used to improve the understanding of the mechanisms driving the inflammatory response and its effects on the sympathetic and parasympathetic pathways of the autonomic nervous system. Autonomic imbalances in patients with Long COVID may result in lower heart rate variability, impaired vagal activity, and substantial sympathovagal imbalance. New research on this subject must be encouraged to enhance the understanding of the long-term risks that cardiovascular autonomic imbalances can cause in individuals with Long COVID.

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

Background

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.

Methods

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.

Findings

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.

Interpretation

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.

Funding

C. S. was supported by a grant from the Weidenhammer-Zoebele Foundation. F. K. was supported by the Volkswagen Foundation.

Hematological alterations associated with long COVID-19

Long COVID-19 is a condition characterized by persistent symptoms lasting beyond the acute phase of COVID-19. Long COVID-19 produces diverse symptomatology and can impact organs and systems, including the hematological system. Several studies have reported, in COVID-19 patients, hematological abnormalities. Most of these alterations are associated with a higher risk of severe disease and poor outcomes. This literature review identified studies reporting hematological parameters in individuals with Long COVID-19. Findings suggest that Long COVID-19 is associated with a range of sustained hematological alterations, including alterations in red blood cells, anemia, lymphopenia, and elevated levels of inflammatory markers such as ferritin, D-dimer, and IL-6. These alterations may contribute to a better understanding of the pathophysiology of Long COVID-19 and its associated symptoms. However, further research is needed to elucidate the underlying mechanisms and potential treatments for these hematological changes in individuals with Long COVID-19.

Utility of Serum Ferritin for Predicting Myalgic Encephalomyelitis/Chronic Fatigue Syndrome in Patients with Long COVID

OBJECTIVE

The most common symptom of post-acute coronavirus disease 2019 (COVID-19) is fatigue, and it potentially leads to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS); however, a specific prognosticator is lacking. We aimed to elucidate the clinical characteristics of patients who developed ME/CFS after COVID-19.

METHODS

In this retrospective observational study, patients who visited Okayama University Hospital for long COVID between February 2021 and March 2022 were investigated.

RESULTS

Of the 234 patients, 139 (59.4%) had fatigue symptoms. Fifty patients with fatigue symptoms (21.4%) met the criteria for ME/CFS (ME/CFS group), while the other 89 patients did not (non-ME/CFS group); 95 patients had no fatigue complaints (no-fatigue group). Although the patients' backgrounds were not significantly different between the three groups, the ME/CFS group presented the highest scores on the self-rating symptom scales, including the Fatigue Assessment Scale (FAS), EuroQol, and the Self-Rating Depression Scale (SDS). Furthermore, serum ferritin levels, which were correlated with FAS and SDS scores, were significantly higher in the ME/CFS group (193.0 μg/L, interquartile range (IQR): 58.8-353.8) than in the non-ME/CFS group (98.2 μg/L, 40.4-251.5) and no-fatigue group (86.7 μg/L, 37.5-209.0), and a high serum ferritin level was prominent in female patients. Endocrine workup further showed that the ME/CFS group had higher thyrotropin levels but lower growth hormone levels in serum and that insulin-like growth factor-I levels were inversely correlated with ferritin levels (R = -0.328, p < 0.05).

CONCLUSIONS

Serum ferritin level is a possible predictor of the development of ME/CFS related to long COVID, especially in female patients.

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.

Long-term hypercoagulability, endotheliopathy and inflammation following acute SARS-CoV-2 infection

INTRODUCTION

both symptomatic and asymptomatic SARS-CoV-2 infections - coined Coronavirus disease 2019 (COVID-19) - have been linked to a higher risk of cardiovascular events after recovery.

AREAS COVERED

our review aims to summarize the latest evidence on the increased thrombotic and cardiovascular risk in recovered COVID-19 patients and to examine the pathophysiological mechanisms underlying the interplay among endothelial dysfunction, inflammatory response and coagulation in long-COVID. We performed a systematic search of studies on hypercoagulability, endothelial dysfunction and inflammation after SARS-CoV-2 infection.

EXPERT OPINION

endothelial dysfunction is a major pathophysiological mechanism responsible for most clinical manifestations in COVID-19. The pathological activation of endothelial cells by a virus infection results in a pro-adhesive and chemokine-secreting phenotype, which in turn promotes the recruitment of circulating leukocytes. Cardiovascular events after COVID-19 appear to be related to persistent immune dysregulation. Patients with long-lasting symptoms display higher amounts of proinflammatory molecules such as tumor necrosis factor-α, interferon γ and interleukins 2 and 6. Immune dysregulation can trigger the activation of the coagulation pathway. The formation of extensive microclots in vivo, both during acute COVID-19 and in long-COVID-19, appears to be a relevant mechanism responsible for persistent symptoms and cardiovascular events.

Promising Markers of Inflammatory and Gut Dysbiosis in Patients with Post-COVID-19 Syndrome

Post-COVID-19 syndrome is a complex of different symptoms, which results in a multisystemic impairment after the suffering from COVID-19 infection. The aim of the study was to reveal the clinical, laboratory, and gut disorders in patients with post-COVID-19 syndrome (n = 39) before and after taking part in the 14-day complex program of rehabilitation. A complete blood count, coagulation test, blood chemistry, biomarkers, and metabolites in serum samples, and gut dysbiosis were revealed in patients on the day of admission and after 14-day rehabilitation, in comparison with the variables of healthy volunteers (n = 48) or with reference ranges. On the day of discharge, patients noted an improvement in respiratory function, general well-being, and mood. At the same time, the levels of some metabolic (4-hydroxybenzoic, succinic, fumaric acids) and inflammatory (interleukin-6) variables, which were increased on admission, did not reach the level of healthy people during the rehabilitation program. Taxonomy disbalance was observed in patients' feces, namely, a high level of total bacterial mass, a decrease in the number of Lactobacillus spp., and an increase in pro-inflammatory microorganisms. The authors suggest that the post-COVID-19 rehabilitation program should be personalized, considering the patient's state together with not only the baseline levels of biomarkers, but also with the individual taxonomy of the gut microbiota.

Interrelationship between COVID-19 and Coagulopathy: Pathophysiological and Clinical Evidence

Since the first description of COVID-19 infection, among clinical manifestations of the disease, including fever, dyspnea, cough, and fatigue, it was observed a high incidence of thromboembolic events potentially evolving towards acute respiratory distress syndrome (ARDS) and COVID-19-associated-coagulopathy (CAC). The hypercoagulation state is based on an interaction between thrombosis and inflammation. The so-called CAC represents a key aspect in the genesis of organ damage from SARS-CoV-2. The prothrombotic status of COVID-19 can be explained by the increase in coagulation levels of D-dimer, lymphocytes, fibrinogen, interleukin 6 (IL-6), and prothrombin time. Several mechanisms have been hypothesized to explain this hypercoagulable process such as inflammatory cytokine storm, platelet activation, endothelial dysfunction, and stasis for a long time. The purpose of this narrative review is to provide an overview of the current knowledge on the pathogenic mechanisms of coagulopathy that may characterize COVID-19 infection and inform on new areas of research. New vascular therapeutic strategies are also reviewed.

The Effectiveness of Adjuvant Attangaogam (Athanam) Yoga Asana-Pranayamam Practices With Regard to Biochemical, Inflammatory, and Hematological Markers Among COVID-19 Patients at a Tertiary Care Hospital in Southern Tamilnadu

Background and objective Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a highly contagious infectious disease that has affected many countries globally. Attangaogam, known in Sanskrit as "Ashtanga yoga", is a practice associated with the spiritual and cultural heritage of India whose origins can be traced back to the very dawn of civilization; the practice of yoga promotes health, healing, and longevity. This study aimed to analyze the effects of Attangaogam (Athanam) yoga asana-Pranayamam practice on biochemical, inflammatory, and hematological markers in the management of COVID-19. Materials and methods A prospective observational study was conducted from August 2021 to February 2022 among hospitalized adult patients of both sexes who consented to participate and tested positive for COVID-19 reverse transcription-polymerase chain reaction (RT-PCR). Convenience sampling was employed and the study was approved by Institutional Ethics Committee (VMCIEC/74/2021). Clinical details, inflammatory markers, D-dimer, lactate dehydrogenase (LDH), ferritin, procalcitonin (PCT), interleukin 6 (IL-6), and complete blood count (CBC) were analyzed for all the volunteering patients on admission and before commencing yoga-pranayamam practices. Also, the parameters were recorded after practicing the scheduled protocol: on the day of discharge, and after the first and third months of discharge. Microsoft Excel 2013 was used for statistical analysis. Results Of the 76 patients, 32 were followed up regularly; the mean age of the cohort was 50.6 ± 4.95 years, and 62% were males. All the patients attained normal oxygen saturation and got discharged in 7-14 days. The comparison of clinical, hematological, inflammatory, and biochemical investigations between pre- and post-Attangaogam yoga-Pranayamam practice sessions showed statistically significant differences and the patients attained normal levels for all variables within three months except for serum albumin. Conclusion Based on our findings, the practice of Attangaogam yoga-Pranayamam contributed to the successful treatment of COVID-19 with the early restoration of protracted hypermetabolic and hyperinflammatory markers to normal status. The evidence related to biomarkers revealed that the patients attained metabolic normalcy of cell health with the aid of personalized physical rehabilitation counteracting inflammation and promoting tissue repair thanks to holistic natural and innate immunity provided by Attangaogam yoga-pranayamam practices.

Association of serum ferritin with severity and clinical outcome in COVID-19 patients: An observational study in a tertiary healthcare facility

Background

Ferritin, an intracellular protein, has a pivotal role in immune dysregulation. Hyperferritinemia has been associated with higher disease severity and adverse clinical outcomes in COVID-19, including mortality. We aimed to study the association of serum ferritin levels with disease severity and clinical outcomes and its severity prediction potential in COVID-19 patients.

Methods

This retrospective study included 870 adult patients with symptomatic COVID-19 infection hospitalized between July 1, 2020 to December 21, 2020. All the patients had a positive polymerase chain reaction test result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Results

The median age was 55 (IQR:40, 65) years with a male predominance [66.32% (n = 577)], among 870 COVID-19. Of these, 413 (47.47%) had mild COVID-19, and 457 (52.53%) had moderate plus severe COVID-19 disease. Median ferritin levels were significantly high in moderate to severe COVID-19 infection compared to mild [545.8 (326.0, 1046.0) vs 97.3 (52.65-155.5) (p = 0.001)], and in patients who developed a complication compared to without complications [380 (177.05, 863.15) vs 290 (110.9, 635) (p = 0.002). A slight elevation in median ferritin levels was observed in patients who had an ICU stay than non-ICU [326 (129.8, 655) vs 309 (119.1, 684) (p = 0.872)]. The cut-off for ferritin was identified at >287.4 ng/ml for mild versus moderate plus severe COVID-19 infections.

Conclusion

Moderate to severe COVID-19 patients have elevated ferritin levels. Patients with more than 287.4 ng/ml ferritin value would have greater chances of developing moderate to severe COVID-19 infections.

Metabolic Profile of Patients with Long COVID: A Cross-Sectional Study

A significant proportion of patients experience a wide range of symptoms following acute coronavirus disease 2019 (COVID-19). Laboratory analyses of long COVID have demonstrated imbalances in metabolic parameters, suggesting that it is one of the many outcomes induced by long COVID. Therefore, this study aimed to illustrate the clinical and laboratory markers related to the course of the disease in patients with long COVID. Participants were selected using a clinical care programme for long COVID in the Amazon region. Clinical and sociodemographic data and glycaemic, lipid, and inflammatory screening markers were collected, and cross-sectionally analysed between the long COVID-19 outcome groups. Of the 215 participants, most were female and not elderly, and 78 were hospitalised during the acute COVID-19 phase. The main long COVID symptoms reported were fatigue, dyspnoea, and muscle weakness. Our main findings show that abnormal metabolic profiles (such as high body mass index measurement and high triglyceride, glycated haemoglobin A1c, and ferritin levels) are more prevalent in worse long COVID presentations (such as previous hospitalisation and more long-term symptoms). This prevalence may suggest a propensity for patients with long COVID to present abnormalities in the markers involved in cardiometabolic health.

The intersection of obesity and (long) COVID-19: Hypoxia, thrombotic inflammation, and vascular endothelial injury

The role of hypoxia, vascular endothelial injury, and thrombotic inflammation in worsening COVID-19 symptoms has been generally recognized. Damaged vascular endothelium plays a crucial role in forming in situ thrombosis, pulmonary dysfunction, and hypoxemia. Thrombotic inflammation can further aggravate local vascular endothelial injury and affect ventilation and blood flow ratio. According to the results of many studies, obesity is an independent risk factor for a variety of severe respiratory diseases and contributes to high mechanical ventilation rate, high mortality, and slow recovery in COVID-19 patients. This review will explore the mechanisms by which obesity may aggravate the acute phase of COVID-19 and delay long COVID recovery by affecting hypoxia, vascular endothelial injury, and thrombotic inflammation. A systematic search of PubMed database was conducted for papers published since January 2020, using the medical subject headings of "COVID-19" and "long COVID" combined with the following keywords: "obesity," "thrombosis," "endothelial injury," "inflammation," "hypoxia," "treatment," and "anticoagulation." In patients with obesity, the accumulation of central fat restricts the expansion of alveoli, exacerbating the pulmonary dysfunction caused by SARS-CoV-2 invasion, inflammatory damage, and lung edema. Abnormal fat secretion and immune impairment further aggravate the original tissue damage and inflammation diffusion. Obesity weakens baseline vascular endothelium function leading to an early injury and pre-thrombotic state after infection. Enhanced procoagulant activity and microthrombi promote early obstruction of the vascular. Obesity also prolongs the duration of symptoms and increases the risk of sequelae after hospital discharge. Persistent viral presence, long-term inflammation, microclots, and hypoxia may contribute to the development of persistent symptoms, suggesting that patients with obesity are uniquely susceptible to long COVID. Early interventions, including supplemental oxygen, comprehensive antithrombotic therapy, and anti-inflammatory drugs, show effectiveness in many studies in the prevention of serious hypoxia, thromboembolic events, and systemic inflammation, and are therefore recommended to reduce intensive care unit admission, mortality, and sequelae.

Biomarkers in long COVID-19: A systematic review

Purpose

Long COVID, also known as post-acute sequelae of COVID-19, refers to the constellation of long-term symptoms experienced by people suffering persistent symptoms for one or more months after SARS-CoV-2 infection. Blood biomarkers can be altered in long COVID patients; however, biomarkers associated with long COVID symptoms and their roles in disease progression remain undetermined. This study aims to systematically evaluate blood biomarkers that may act as indicators or therapeutic targets for long COVID.

Methods

A systematic literature review in PubMed, Embase, and CINAHL was performed on 18 August 2022. The search keywords long COVID-19 symptoms and biomarkers were used to filter out the eligible studies, which were then carefully evaluated.

Results

Identified from 28 studies and representing six biological classifications, 113 biomarkers were significantly associated with long COVID: (1) Cytokine/Chemokine (38, 33.6%); (2) Biochemical markers (24, 21.2%); (3) Vascular markers (20, 17.7%); (4) Neurological markers (6, 5.3%); (5) Acute phase protein (5, 4.4%); and (6) Others (20, 17.7%). Compared with healthy control or recovered patients without long COVID symptoms, 79 biomarkers were increased, 29 were decreased, and 5 required further determination in the long COVID patients. Of these, up-regulated Interleukin 6, C-reactive protein, and tumor necrosis factor alpha might serve as the potential diagnostic biomarkers for long COVID. Moreover, long COVID patients with neurological symptoms exhibited higher levels of neurofilament light chain and glial fibrillary acidic protein whereas those with pulmonary symptoms exhibited a higher level of transforming growth factor beta.

Conclusion

Long COVID patients present elevated inflammatory biomarkers after initial infection. Our study found significant associations between specific biomarkers and long COVID symptoms. Further investigations are warranted to identify a core set of blood biomarkers that can be used to diagnose and manage long COVID patients in clinical practice.

Ultrasonographic findings in long COVID: A cross-sectional study of 312 patients

Background

Fatigue and muscle weakness are common complaints in COVID-19 survivors. However, little is still known about the skeletal muscle qualitative and quantitative characteristics after hospitalization due to moderate and severe COVID-19.

Objectives

To assess rectus femoris and vastus intermedius muscle thickness (MT) and rectus femoris echo intensity (EI) and to establish its association with demographic, clinical, functional, and inflammatory parameters in long COVID patients after hospital discharge.

Methods

Cross-sectional study with 312 COVID-19 patients (53.53% male; age: 54.59 ± 13.50 years), with a laboratory-confirmed diagnosis of COVID-19. Patients were assessed 3-11 months after hospital discharge. We evaluated MT of the right rectus femoris and vastus intermedius and EI of the right rectus femoris using a portable ultrasound system, 6-13 MHz, broadband linear transducer. We corrected EI using the subcutaneous fat thickness. Ultrasonographic parameters were tested in association with demographic (sex and age); functional (Handgrip strength measurement, Timed Up and Go, 1 min Sit-to-Stand test, EuroQoL-5 Dimensions-5 Levels, World Health Organization Disability Assessment Schedule (WHODAS 2.0), Post-COVID-19 Functional Status, Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT), Medical Research Council (MRC) sum score, Borg Dyspnea Scale, MRC Dyspnea score, Visual Analogue Scale (VAS), Epworth Sleepiness Scale, Insomnia Severity Index, Functional Independence Measurement (FIM), and Functional Oral Intake Scale); clinical (length of hospital stay, intubation, and presence of comorbidities such as systemic hypertension, diabetes, obesity, chronic obstructive pulmonary disease, asthma), and inflammatory data assessed by the C-reactive protein and D-dimer serum concentrations.

Results

Rectus femoris MT was associated with age, handgrip strength, Epworth Sleepiness Scale, and subcutaneous fat thickness (r² = 27.51%; p < 0.0001). Vastus intermedius MT was associated with age, pain intensity, handgrip strength, Epworth Sleepiness scale, FIM, and time since hospital discharge (r² = 21.12%; p < 0.0001). Rectus femoris EI was significantly associated with the male sex, TUG, Epworth Sleepiness Scale, and C-Reactive Protein levels (r² = 44.39%; p < 0.0001). Mean MT of rectus femoris and vastus intermedius are significantly different (p < 0.001).

Conclusion

After hospital discharge, long COVID patients present qualitative and quantitative skeletal muscle characteristics associated with a combination of demographic, clinical, and functional parameters.

Iron Dyshomeostasis in COVID-19: Biomarkers Reveal a Functional Link to 5-Lipoxygenase Activation

Coronavirus disease 2019 (COVID-19) is characterized by a broad spectrum of clinical symptoms. After acute infection, some subjects develop a post-COVID-19 syndrome known as long-COVID. This study aims to recognize the molecular and functional mechanisms that occur in COVID-19 and long-COVID patients and identify useful biomarkers for the management of patients with COVID-19 and long-COVID. Here, we profiled the response to COVID-19 by performing a proteomic analysis of lymphocytes isolated from patients. We identified significant changes in proteins involved in iron metabolism using different biochemical analyses, considering ceruloplasmin (Cp), transferrin (Tf), hemopexin (HPX), lipocalin 2 (LCN2), and superoxide dismutase 1 (SOD1). Moreover, our results show an activation of 5-lipoxygenase (5-LOX) in COVID-19 and in long-COVID possibly through an iron-dependent post-translational mechanism. Furthermore, this work defines leukotriene B4 (LTB4) and lipocalin 2 (LCN2) as possible markers of COVID-19 and long-COVID and suggests novel opportunities for prevention and treatment.

Molecular and cellular mechanisms involved in tissue-specific metabolic modulation by SARS-CoV-2

Coronavirus disease 2019 (COVID-19) is triggered by the SARS-CoV-2, which is able to infect and cause dysfunction not only in lungs, but also in multiple organs, including central nervous system, skeletal muscle, kidneys, heart, liver, and intestine. Several metabolic disturbances are associated with cell damage or tissue injury, but the mechanisms involved are not yet fully elucidated. Some potential mechanisms involved in the COVID-19-induced tissue dysfunction are proposed, such as: (a) High expression and levels of proinflammatory cytokines, including TNF-α IL-6, IL-1β, INF-α and INF-β, increasing the systemic and tissue inflammatory state; (b) Induction of oxidative stress due to redox imbalance, resulting in cell injury or death induced by elevated production of reactive oxygen species; and (c) Deregulation of the renin-angiotensin-aldosterone system, exacerbating the inflammatory and oxidative stress responses. In this review, we discuss the main metabolic disturbances observed in different target tissues of SARS-CoV-2 and the potential mechanisms involved in these changes associated with the tissue dysfunction.

Mindfulness Meditation Interventions for Long COVID: Biobehavioral Gene Expression and Neuroimmune Functioning

Some individuals infected with SARS CoV-2 have developed Post-Acute Sequelae of SARS CoV-2 infection (PASC) or what has been referred to as Long COVID. Efforts are underway to find effective treatment strategies for those with Long COVID. One possible approach involves alternative medical interventions, which have been widely used to treat and manage symptoms of a variety of medical problems including post-viral infections. Meditation has been found to reduce fatigue and unrefreshing sleep, and for those with post-viral infections, it has enhanced immunity, and reduced inflammatory-driven pathogenesis. Our article summarizes the literature on what is known about mindfulness meditation interventions, and reviews evidence on how it may apply to those with Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Evidence is reviewed suggesting effective and sustainable outcomes may be achieved for symptomatology and underlying pathology of post-viral fatigue (PASC and ME/CFS).

The Challenge of Long COVID-19 Management: From Disease Molecular Hallmarks to the Proposal of Exercise as Therapy

Long coronavirus disease 19 (COVID-19) is the designation given to a novel syndrome that develops within a few months after infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and that is presenting with increasing incidence because of the numerous cases of infection. Long COVID-19 is characterized by a sequela of clinical symptoms that concern different organs and tissues, from nervous, respiratory, gastrointestinal, and renal systems to skeletal muscle and cardiovascular apparatus. The main common molecular cause for all long COVID-19 facets appears to be related to immune dysregulations, the persistence of inflammatory status, epigenetic modifications, and alterations of neurotrophin release. The prevention and management of long COVID-19 are still inappropriate because many aspects need further clarification. Exercise is known to exert a deep action on molecular dysfunctions elicited by long COVID-19 depending on training intensity, duration, and continuity. Evidence suggests that it could improve the quality of life of long COVID-19 patients. This review explores the main clinical features and the known molecular mechanisms underlying long COVID-19 in the perspective of considering exercise as a co-medication in long COVID-19 management.

The impact of platelets on pulmonary microcirculation throughout COVID-19 and its persistent activating factors

Patients with COVID-19 often have hypoxemia, impaired lung function, and abnormal imaging manifestations in acute and convalescent stages. Alveolar inflammation, pulmonary vasculitis, and thromboembolism synergistically damage the blood-air barrier, resulting in increased pulmonary permeability and gas exchange disorders. The incidence of low platelet counts correlates with disease severity. Platelets are also involved in the impairment of pulmonary microcirculation leading to abnormal lung function at different phases of COVID-19. Activated platelets lose the ability to protect the integrity of blood vessel walls, increasing the permeability of pulmonary microvasculature. High levels of platelet activation markers are observed in both mild and severe cases, short and long term. Therefore, the risk of thrombotic events may always be present. Vascular endothelial injury, immune cells, inflammatory mediators, and hypoxia participate in the high reactivity and aggregation of platelets in various ways. Microvesicles, phosphatidylserine (PS), platelets, and coagulation factors are closely related. The release of various cell-derived microvesicles can be detected in COVID-19 patients. In addition to providing a phospholipid surface for the synthesis of intrinsic factor Xase complex and prothrombinase complex, exposed PS also promotes the decryption of tissue factor (TF) which then promotes coagulant activity by complexing with factor VIIa to activate factor X. The treatment of COVID-19 hypercoagulability and thrombosis still focuses on early intervention. Antiplatelet therapy plays a role in relieving the disease, inhibiting the formation of the hypercoagulable state, reducing thrombotic events and mortality, and improving sequelae. PS can be another potential target for the inhibition of hypercoagulable states.

Long COVID: a narrative review of the clinical aftermaths of COVID-19 with a focus on the putative pathophysiology and aspects of physical activity

The pandemic coronavirus disease 2019 (COVID-19) can cause multi-systemic symptoms that can persist beyond the acute symptomatic phase. The post-acute sequelae of COVID-19 (PASC), also referred to as long COVID, describe the persistence of symptoms and/or long-term complications beyond 4 weeks from the onset of the acute symptoms and are estimated to affect at least 20% of the individuals infected with SARS-CoV-2 regardless of their acute disease severity. The multi-faceted clinical picture of long COVID encompasses a plethora of undulating clinical manifestations impacting various body systems such as fatigue, headache, attention disorder, hair loss and exercise intolerance. The physiological response to exercise testing is characterized by a reduced aerobic capacity, cardiocirculatory limitations, dysfunctional breathing patterns and an impaired ability to extract and use oxygen. Still, to this day, the causative pathophysiological mechanisms of long COVID remain to be elucidated, with long-term organ damage, immune system dysregulation and endotheliopathy being among the hypotheses discussed. Likewise, there is still a paucity of treatment options and evidence-based strategies for the management of the symptoms. In sum, this review explores different aspects of long COVID and maps the literature on what is known about its clinical manifestations, potential pathophysiological mechanisms, and treatment options.

Post-acute sequelae of SARS-CoV-2 infection: relationship of central nervous system manifestations with physical disability and systemic inflammation

BACKGROUND

Despite the multitude of clinical manifestations of post-acute sequelae of SARS-CoV-2 infection (PASC), studies applying statistical methods to directly investigate patterns of symptom co-occurrence and their biological correlates are scarce.

METHODS

We assessed 30 symptoms pertaining to different organ systems in 749 adults (age = 55 ± 14 years; 47% female) during in-person visits conducted at 6-11 months after hospitalization due to coronavirus disease 2019 (COVID-19), including six psychiatric and cognitive manifestations. Symptom co-occurrence was initially investigated using exploratory factor analysis (EFA), and latent variable modeling was then conducted using Item Response Theory (IRT). We investigated associations of latent variable severity with objective indices of persistent physical disability, pulmonary and kidney dysfunction, and C-reactive protein and D-dimer blood levels, measured at the same follow-up assessment.

RESULTS

The EFA extracted one factor, explaining 64.8% of variance; loadings were positive for all symptoms, and above 0.35 for 16 of them. The latent trait generated using IRT placed fatigue, psychiatric, and cognitive manifestations as the most discriminative symptoms (coefficients > 1.5, p < 0.001). Latent trait severity was associated with decreased body weight and poorer physical performance (coefficients > 0.240; p ⩽ 0.003), and elevated blood levels of C-reactive protein (coefficient = 0.378; 95% CI 0.215-0.541; p < 0.001) and D-dimer (coefficient = 0.412; 95% CI 0.123-0.702; p = 0.005). Results were similar after excluding subjects with pro-inflammatory comorbidities.

CONCLUSIONS

Different symptoms that persist for several months after moderate or severe COVID-19 may unite within one latent trait of PASC. This trait is dominated by fatigue and psychiatric symptoms, and is associated with objective signs of physical disability and persistent systemic inflammation.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia–reperfusion (I–R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I–R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Long COVID and the cardiovascular system - elucidating causes and cellular mechanisms in order to develop targeted diagnostic and therapeutic strategies: A joint Scientific Statement of the ESC Working Groups on Cellular Biology of the Heart and Myocardial & Pericardial Diseases

Long COVID has become a world-wide, non-communicable epidemic, caused by long-lasting multi-organ symptoms that endure for weeks or months after SARS-CoV-2 infection has already subsided. This scientific document aims to provide insight into the possible causes and therapeutic options available for the cardiovascular manifestations of long COVID. In addition to chronic fatigue, which is a common symptom of long COVID, patients may present with chest pain, ECG abnormalities, postural orthostatic tachycardia, or newly developed supraventricular or ventricular arrhythmias. Imaging of the heart and vessels has provided evidence of chronic, post-infectious peri-myocarditis with consequent left or right ventricular failure, arterial wall inflammation or micro-thrombosis in certain patient populations. Better understanding of the underlying cellular and molecular mechanisms of long COVID will aid in the development of effective treatment strategies for its cardiovascular manifestations. A number of mechanisms have been proposed, including those involving direct effects on the myocardium, micro-thrombotic damage to vessels or endothelium, or persistent inflammation. Unfortunately, existing circulating biomarkers, coagulation and inflammatory markers, are not highly predictive for either the presence or outcome of long COVID when measured 3 months after SARS-CoV-2 infection. Further studies are needed to understand underlying mechanisms, identify specific biomarkers and guide future preventive strategies or treatments to address long COVID and its cardiovascular sequelae.

Persistent Lung Injury and Prothrombotic State in Long COVID

Lung injury may persist during the recovery period of COVID-19 as shown through imaging, six-minute walk, and lung function tests. The pathophysiological mechanisms leading to long COVID have not been adequately explained. Our aim is to investigate the basis of pulmonary susceptibility during sequelae and the possibility that prothrombotic states may influence long-term pulmonary symptoms of COVID-19. The patient’s lungs remain vulnerable during the recovery stage due to persistent shedding of the virus, the inflammatory environment, the prothrombotic state, and injury and subsequent repair of the blood-air barrier. The transformation of inflammation to proliferation and fibrosis, hypoxia-involved vascular remodeling, vascular endothelial cell damage, phosphatidylserine-involved hypercoagulability, and continuous changes in serological markers all contribute to post-discharge lung injury. Considering the important role of microthrombus and arteriovenous thrombus in the process of pulmonary functional lesions to organic lesions, we further study the possibility that prothrombotic states, including pulmonary vascular endothelial cell activation and hypercoagulability, may affect long-term pulmonary symptoms in long COVID. Early use of combined anticoagulant and antiplatelet therapy is a promising approach to reduce the incidence of pulmonary sequelae. Essentially, early treatment can block the occurrence of thrombotic events. Because impeded pulmonary circulation causes large pressure imbalances over the alveolar membrane leading to the infiltration of plasma into the alveolar cavity, inhibition of thrombotic events can prevent pulmonary hypertension, formation of lung hyaline membranes, and lung consolidation.

Long COVID: The Nature of Thrombotic Sequelae Determines the Necessity of Early Anticoagulation

Many discharged COVID-19 patients affected by sequelae experience reduced quality of life leading to an increased burden on the healthcare system, their families and society at large. Possible pathophysiological mechanisms of long COVID include: persistent viral replication, chronic hypoxia and inflammation. Ongoing vascular endothelial damage promotes platelet adhesion and coagulation, resulting in the impairment of various organ functions. Meanwhile, thrombosis will further aggravate vasculitis contributing to further deterioration. Thus, long COVID is essentially a thrombotic sequela. Unfortunately, there is currently no effective treatment for long COVID. This article summarizes the evidence for coagulation abnormalities in long COVID, with a focus on the pathophysiological mechanisms of thrombosis. Extracellular vesicles (EVs) released by various types of cells can carry SARS-CoV-2 through the circulation and attack distant tissues and organs. Furthermore, EVs express tissue factor and phosphatidylserine (PS) which aggravate thrombosis. Given the persistence of the virus, chronic inflammation and endothelial damage are inevitable. Pulmonary structural changes such as hypertension, embolism and fibrosis are common in long COVID. The resulting impaired lung function and chronic hypoxia again aggravates vascular inflammation and coagulation abnormalities. In this article, we also summarize recent research on antithrombotic therapy in COVID-19. There is increasing evidence that early anticoagulation can be effective in improving outcomes. In fact, persistent systemic vascular inflammation and dysfunction caused by thrombosis are key factors driving various complications of long COVID. Early prophylactic anticoagulation can prevent the release of or remove procoagulant substances, thereby protecting the vascular endothelium from damage, reducing thrombotic sequelae, and improving quality of life for long-COVID patients.

Long COVID: post-acute sequelae of COVID-19 with a cardiovascular focus

Emerging as a new epidemic, long COVID or post-acute sequelae of coronavirus disease 2019 (COVID-19), a condition characterized by the persistence of COVID-19 symptoms beyond 3 months, is anticipated to substantially alter the lives of millions of people globally. Cardiopulmonary symptoms including chest pain, shortness of breath, fatigue, and autonomic manifestations such as postural orthostatic tachycardia are common and associated with significant disability, heightened anxiety, and public awareness. A range of cardiovascular (CV) abnormalities has been reported among patients beyond the acute phase and include myocardial inflammation, myocardial infarction, right ventricular dysfunction, and arrhythmias. Pathophysiological mechanisms for delayed complications are still poorly understood, with a dissociation seen between ongoing symptoms and objective measures of cardiopulmonary health. COVID-19 is anticipated to alter the long-term trajectory of many chronic cardiac diseases which are abundant in those at risk of severe disease. In this review, we discuss the definition of long COVID and its epidemiology, with an emphasis on cardiopulmonary symptoms. We further review the pathophysiological mechanisms underlying acute and chronic CV injury, the range of post-acute CV sequelae, and impact of COVID-19 on multiorgan health. We propose a possible model for referral of post-COVID-19 patients to cardiac services and discuss future directions including research priorities and clinical trials that are currently underway to evaluate the efficacy of treatment strategies for long COVID and associated CV sequelae.

Long COVID in hospitalized and non-hospitalized patients in a large cohort in Northwest Spain, a prospective cohort study

Survivors to COVID-19 have described long-term symptoms after acute disease. These signs constitute a heterogeneous group named long COVID or persistent COVID. The aim of this study is to describe persisting symptoms 6 months after COVID-19 diagnosis in a prospective cohort in the Northwest Spain. This is a prospective cohort study performed in the COHVID-GS. This cohort includes patients in clinical follow-up in a health area of 569,534 inhabitants after SARS-CoV-2/COVID-19 diagnosis. Clinical and epidemiological characteristics were collected during the follow up. A total of 248 patients completed 6 months follow-up, 176 (69.4%) required hospitalization and 29 (10.2%) of them needed critical care. At 6 months, 119 (48.0%) patients described one or more persisting symptoms. The most prevalent were: extra-thoracic symptoms (39.1%), chest symptoms (27%), dyspnoea (20.6%), and fatigue (16.1%). These symptoms were more common in hospitalized patients (52.3% vs. 38.2%) and in women (59.0% vs. 40.5%). The multivariate analysis identified COPD, women gender and tobacco consumption as risk factors for long COVID. Persisting symptoms are common after COVID-19 especially in hospitalized patients compared to outpatients (52.3% vs. 38.2%). Based on these findings, special attention and clinical follow-up after acute SARS-CoV-2 infection should be provided for hospitalized patients with previous lung diseases, tobacco consumption, and women.

Implication of COVID-19 on Erythrocytes Functionality: Red Blood Cell Biochemical Implications and Morpho-Functional Aspects

Several diseases (such as diabetes, cancer, and neurodegenerative disorders) affect the morpho-functional aspects of red blood cells, sometimes altering their normal metabolism. In this review, the hematological changes are evaluated, with particular focus on the morphology and metabolic aspects of erythrocytes. Changes in the functionality of such cells may, in fact, help provide important information about disease severity and progression. The viral infection causes significant damage to the blood cells that are altered in size, rigidity, and distribution width. Lower levels of hemoglobin and anemia have been reported in several studies, and an alteration in the concentration of antioxidant enzymes has been shown to promote a dangerous state of oxidative stress in red blood cells. Patients with severe COVID-19 showed an increase in hematological changes, indicating a progressive worsening as COVID-19 severity progressed. Therefore, monitored hematological alterations in patients with COVID-19 may play an important role in the management of the disease and prevent the risk of a severe course of the disease. Finally, monitored changes in erythrocytes and blood, in general, may be one of the causes of the condition known as Long COVID.