Tag: 2026

Recovery trajectories and predictors of symptom resolution in post-COVID-19 condition: a population-based cohort study

Abstract:

Background: SARS-CoV-2 infection can lead to persistent symptoms, known as Post-COVID-19 Condition (PCC). Previous studies on PCC prognosis mainly looked at severe cases in rehabilitation settings and without knowledge about pre-infection symptom levels. Uncertainty remains about recovery trajectory in the general population, its predictors, and whether recovery differs by symptom.

Methods: We analysed data from Lifelines, a prospective population-based observational cohort. Adults completed 31 COVID-19 questionnaires between March 2020 and October 2022 providing longitudinal symptom data to assess PCC status, and recovery. PCC was defined as at least one moderately severe symptom, among 12 identified as PCC-specific, that worsened 90-150 days after infection. Cox-proportional hazard models estimated recovery, defined as symptom decline to an individual’s pre-infection baseline, adjusted for symptoms present at PCC diagnosis, age, sex, BMI, smoking, hospitalization, vaccination, and comorbidities.

Findings: We analysed time series of 809 cases (mean age 55.0; [SD 11.0]; 590 [73%] female; mean follow up 368 days; [SD 200]). Symptom decline to pre-infection baseline or below was observed in 558 participants; the Kaplan-Meier 24-month symptom decline estimate was 92%. Greater symptom burden was associated with a lower likelihood of recovery (HR per additional symptom 0.69, 95% CI 0.63-0.76), whereas younger age had a higher likelihood of recovery compared with middle adulthood (HR 1.52, 95% CI 1.06-2.18). Median time to symptom decline was 226 days (IQR 182-372), with most improvement within the first 235 days before slowing and plateauing.

Interpretation: Most individuals with PCC recover, but older adults and those with multiple symptoms are at higher risk of prolonged illness, underscoring the need for ongoing support.

Source: Brunet JL, van Ockenburg SL, Leyli-Abadi M, Lunter G, Rosmalen JGM. Recovery trajectories and predictors of symptom resolution in post-COVID-19 condition: a population-based cohort study. Lancet Reg Health Eur. 2026 Aug 8;69:101802. doi: 10.1016/j.lanepe.2026.101802. PMID: 42604070; PMCID: PMC13476563. https://pmc.ncbi.nlm.nih.gov/articles/PMC13476563/ (Full text)

Transforming biomedical uncertainty: the sociohistorical origins of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS)

Abstract:

Myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are serious and disabling long-term conditions characterised by uncertainty surrounding their aetiology, diagnosis and treatment. People with ME/CFS struggle to be understood, taken seriously and supported with their illness. At least since the 1990s, ME and CFS have been considered by many to be related, overlapping or synonymous with one another. However, the concepts originated from different sociohistorical contexts. This article disentangles the histories of ME and CFS, roots them in the UK and the USA respectively, and compares how they emerged as medical and scientific objects.

Drawing on a critical literature analysis of medical texts between 1950 and 1990, I explore how both ME and CFS materialised through the regulation of uncertainty within biomedical systems. In both cases, uncertainty was transformed into knowledge by systematically obscuring certain aspects of illness. These transformations shaped what could be known about these conditions in the decades to come and may be at the root of the epistemic injustices experienced by patients.

Those who campaign for more scientific research into ME/CFS should be wary of the propensity for biomedicine to generate ignorance in the face of these complex conditions. This analysis contributes to a growing body of research on the medical sociology of ignorance, further illustrating the value of uncertainty and ignorance as heuristic tools for understanding the politics of knowledge production within biomedical systems.

Source: Cross S. Transforming biomedical uncertainty: the sociohistorical origins of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Med Humanit. 2026 Aug 14:medhum-2025-013657. doi: 10.1136/medhum-2025-013657. Epub ahead of print. PMID: 42601195. https://pubmed.ncbi.nlm.nih.gov/42601195/

REenergizeME: intermittent hypoxia-hyperoxia treatment for myalgic encephalomyelitis/chronic fatigue syndrome-protocol for a randomised, placebo-controlled trial

Abstract:

Introduction: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic, disabling condition characterised by post-exertional malaise (PEM), autonomic dysfunction and markedly reduced quality of life. Its prevalence has increased following the COVID-19 pandemic, yet no effective disease-modifying treatments are available and underlying mechanisms remain unclear. Evidence implicates immune-metabolic dysregulation, impaired energy metabolism, vascular dysfunction and altered oxygen handling. Intermittent hypoxia-hyperoxia treatment (IHHT) is a non-pharmacological intervention proposed to induce adaptive physiological and cellular responses via hypoxia- and redox-sensitive pathways. This trial evaluates the clinical efficacy of IHHT in ME/CFS and explores associated mechanisms.

Methods and analysis: This randomised, placebo-controlled, participant- and assessor-blinded clinical trial will enrol 104 female patients aged 20-59 years who meet the International Consensus Criteria for ME/CFS along with a healthy control group for mechanistic comparisons. Participants will be randomised 1:1 to IHHT or placebo following baseline assessments. The intervention will be delivered over 8 weeks. The primary endpoint is change in quality of life measured by the vitality domain of the Short Form-36 Health Survey. Secondary endpoints include PEM severity, fatigue severity, cognitive severity, functional capacity and autonomic symptoms assessed using validated patient-reported outcome measures and objective tests. Exploratory endpoints include pain phenotyping, autonomic, sudomotor and neurophysiological assessments, tissue oxygenation by near-infrared spectroscopy, peripheral small-fibre nerve assessments using corneal confocal microscopy and skin biopsy and immune-metabolic and oxidative stress biomarkers. Assessments will be conducted at baseline; post-treatment; and at 3, 6 and 12 months follow-up.

Ethics and dissemination: The trial is conducted in accordance with the Declaration of Helsinki and International Council for Harmonisation – Good Clinical Practice guidelines and was approved by the Danish Scientific Ethical Committees (De Videnskabsetiske Medicinske Komitéer, VMK; approval no. 2500959). Written informed consent will be obtained from all participants. Results will be disseminated through peer-reviewed publications and scientific conferences.

Trial registration number: ClinicalTrials.gov Identifier: NCT07317401.

Source: Nochi M, Kristensen SK, Mehrani N, Guerreiro I, Nørholm IMD, Chandra S, Olufsen M, Gudbergsen LR, Brinth LS, Stokholm R, Karlsson P, Tankisi H, Mehlsen J, Foldager CB, Olsen RKJ. REenergizeME: intermittent hypoxia-hyperoxia treatment for myalgic encephalomyelitis/chronic fatigue syndrome-protocol for a randomised, placebo-controlled trial. BMJ Open. 2026 Aug 14;16(8):e117729. doi: 10.1136/bmjopen-2026-117729. PMID: 42601095. https://bmjopen.bmj.com/content/16/8/e117729 (Full text)

ME/CFS and the emotional toll of persistent disbelief: from epistemic to affective injustice

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating chronic illness whose sufferers are frequently met with disbelief, stigmatization, and psychologization in both clinical and social contexts. Recent work has used the concept of “epistemic injustice” to illuminate important dimensions of this problem, especially the ways in which ME/CFS patients are discredited as knowers and denied adequate interpretive resources.

This paper argues that the harms associated with persistent disbelief in ME/CFS are not exhausted by this epistemic dimension. Drawing on recent philosophical work on affective injustice, I argue that persistent disbelief can also impair patients’ affective lives in distinctive and socially patterned ways.

More specifically, I argue that individuals with ME/CFS are burdened by unjust affective expectations, pressured into norm-conforming forms of emotional self-presentation, exposed to pathologizing and gaslighting interpretations of their affective experience, denied uptake for apt emotional responses, and exploited through forms of emotional labor and affective appropriation. Conceptualizing these harms in terms of affective injustice, I argue, helps to capture dimensions of marginalization that a focus on testimony and understanding alone leaves obscure.

The paper concludes by considering objections and drawing out implications for healthcare and philosophy of medicine.

Source: Walter S. ME/CFS and the emotional toll of persistent disbelief: from epistemic to affective injustice. Med Health Care Philos. 2026 Aug 14. doi: 10.1007/s11019-026-10388-6. Epub ahead of print. PMID: 42599643. https://link.springer.com/article/10.1007/s11019-026-10388-6 (Full text)

Orthostatic intolerance with small heart and/or disequilibrium in patients with myalgic encephalomyelitis/chronic fatigue syndrome: clinical update and paradigm shift

Abstract:

Orthostatic intolerance (OI) is characterized by the inability to maintain an upright posture without experiencing severe signs and symptoms, including hypotension, palpitations, light-headedness, pallor, fatigue, weakness, dizziness, impaired concentration, tremulousness, and nausea. The majority of patients with myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) exhibit OI, which is the primary factor restricting daily functional capacity.

During an upright posture, approximately 800 mL of blood is translocated from the intrathoracic venous compartment to the veins of the buttocks, pelvis, and legs. Under normal conditions, compensatory cardiovascular responses to this orthostatic stress include activation of the muscle pump through calf muscle contraction and a neurogenically mediated increase in heart rate and in systemic vascular resistance. The majority of the symptoms of OI are believed to be cardiovascular and related to reduced cerebral blood flow and excessive activation of the sympathetic nervous system.

However, compensatory sympathetic activation is essential for maintaining orthostasis. Many patients have a small left ventricle and associated low cardiac output. In addition, both the renin-aldosterone and antidiuretic hormone systems that regulate circulatory blood volume were downregulated.

Postural stability is necessary for maintaining the static balance critical for performing many daily activities. Recently studies have reported that postural instability or disequilibrium, potentially associated with central vestibular dysfunction, should be considered to be involved in the pathogenesis of OI among patients with ME/CFS. Disequilibrium should be recognized as an important cause of OI in those patients.

Source: Miwa K. Orthostatic intolerance with small heart and/or disequilibrium in patients with myalgic encephalomyelitis/chronic fatigue syndrome: clinical update and paradigm shift. Front Med (Lausanne). 2026 Jul 29;13:1744154. doi: 10.3389/fmed.2026.1744154. PMID: 42591853; PMCID: PMC13463185.  https://pmc.ncbi.nlm.nih.gov/articles/PMC13463185/ (Full text)

Association between myalgic encephalomyelitis/chronic fatigue syndrome and irritable bowel syndrome: a systematic review and meta-analysis

Abstract:

Background: Irritable bowel syndrome (IBS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are chronic, debilitating disorders characterized by substantial symptom burden, impaired quality of life, and high healthcare utilization. IBS is a disorder of gut-brain interaction with a global prevalence ranging from 3.8% to 9.2%, while ME/CFS is defined by persistent, exertion-intolerant fatigue and multisystem dysfunction. Growing evidence suggests frequent co-occurrence of these conditions, implicating shared mechanisms such as immune dysregulation, autonomic imbalance, and altered gut-brain signaling. However, the magnitude of their association has not been comprehensively quantified.

Methods: We conducted a systematic review and meta-analysis by searching Embase, PubMed, Scopus, and Google Scholar databases from inception through February 2026. Eligible observational studies reporting associations or prevalence between IBS and ME/CFS were included. Random-effects meta-analyses were performed to pool odds ratios (ORs) and prevalence estimates. Heterogeneity was assessed using I2 statistics. We evaluated for publication bias and assessed for risk of bias.

Results: Twenty-two studies were included in the systematic review and 18 in the meta-analysis. Individuals with ME/CFS had significantly higher odds of IBS compared with controls (OR = 7.20; 95% CI: 2.77-18.76; I2 = 72.1%). The pooled prevalence of IBS among individuals with ME/CFS was 37% (95% CI: 23-54%), with substantial heterogeneity (I2 = 99.5%). Subgroup analysis revealed that diagnostic criteria significantly influenced prevalence (p < 0.0001), while meta-regression identified ME/CFS diagnostic criteria as a significant moderator.

Conclusion: IBS and ME/CFS are strongly associated, suggesting shared underlying mechanisms. These findings support integrated screening approaches and coordinated, multidisciplinary management to improve outcomes in affected patients.

Source: Rajabi N, Ramdass PVAK. Association between myalgic encephalomyelitis/chronic fatigue syndrome and irritable bowel syndrome: a systematic review and meta-analysis. Front Med (Lausanne). 2026 Jul 27;13:1881784. doi: 10.3389/fmed.2026.1881784. PMID: 42577233; PMCID: PMC13453825. https://pmc.ncbi.nlm.nih.gov/articles/PMC13453825/ (Full text)

Haptoglobin Phenotypes Stratify Post-Exertional Cognitive Dysfunction Associated with Altered Cerebral Oxygenation and Metabolic Signatures in Long COVID

Abstract:

Long COVID (LC) is a heterogeneous post-infectious syndrome characterized by persistent symptoms, yet the biological basis underlying its interindividual variability remains poorly understood. Given the clinical overlap between LC and myalgic encephalomyelitis (ME), and prior demonstration that haptoglobin (Hp) phenotypes modulate symptom severity in ME, we investigated whether Hp phenotypes similarly stratify post-exertional cognitive dysfunction in LC.
In this longitudinal observational study, 44 individuals with LC and 20 short-course COVID controls, who recovered rapidly from SARS-CoV-2 infection without persistent symptoms or sequelae, underwent Hp phenotyping alongside metabolomic and physiological profiling before and after a standardized 90 min passive post-exertional challenge. Hp phenotypes identified clinically distinct LC subgroups.
Compared with Hp1-1 individuals, Hp2 allele carriers exhibited greater fatigue, poorer physical function, and more severe post-exertional symptoms. Immediately following the challenge, Hp2-2 participants with LC showed significant cognitive decline, whereas Hp1-1 individuals demonstrated cognitive resilience and more favorable longitudinal cognitive trajectories.
This differential susceptibility was accompanied by higher post-exertional cerebral fractional tissue oxygen extraction in the right hemisphere in Hp1-1 individuals and by distinct metabolic signatures, with Hp2 allele carriers exhibiting lower post-exertional plasma concentrations of citric acid, isethionate, and glucosamine. Lower metabolite levels were associated with poorer cognitive performance.
These findings support Hp phenotypes as promising candidate biomarkers for biological stratification in Long COVID, pending validation in larger independent cohorts.

Source: Moezzi A, Elremaly W, Leveau C, Franco A, Nepotchatykh O, Armstrong CW, Moreau A. Haptoglobin Phenotypes Stratify Post-Exertional Cognitive Dysfunction Associated with Altered Cerebral Oxygenation and Metabolic Signatures in Long COVID. International Journal of Molecular Sciences. 2026; 27(15):7000. https://doi.org/10.3390/ijms27157000 https://www.mdpi.com/1422-0067/27/15/7000 (Full text)

Peripheral blood cytokines during early and post-acute stages of SARS-CoV-2 infection are associated with disease severity and long-term symptoms

Abstract:

Background: U.S. Veterans experience a high burden of COVID-19; characterizing immune responses associated with COVID-19 outcomes could help improve treatment. Changes in peripheral blood cytokines over time may predict both acute outcomes and long COVID symptoms.

Methods: Cytokine concentrations were quantified from peripheral blood collected 0-7 days (early) and 14-42 days (post-acute) after enrollment from SARS-CoV-2 positive participants in the EPIC3 study, a prospective, longitudinal cohort following U.S. Veterans. Responses were correlated with Veterans Affairs Severity Index for COVID-19 criteria and chronic symptoms with the modified Medical Research Council Dyspnea scale, Patient-Reported Outcomes Measurement Information System (PROMIS) Cognitive function, and PROMIS Fatigue scores 3 months after enrollment (60-135 days). Trends in cytokine concentration with COVID-19 severity were assessed. Odds of COVID-19 severity and long-term symptoms were estimated with logistic regression adjusted for sex, age, and morbidity. Longitudinal changes in cytokine concentration were examined for participants sampled during both time periods, by severity and long-term symptom group.

Results: Early HGF, IL-18, IL-1RA, IP-10, and VEGF-A and post-acute MIP-1α and VEGF-A concentrations trended positively with increasing COVID-19 severity (q-values < 0.05, Jonckheere-Terpstra trend test). Increases in EGF, MIP-1β, and RANTES concentration and decreases in MIP-1α concentration over time were associated with mild rather than moderate or severe disease. Increases in MIP-1β and RANTES concentration and decreases in Eotaxin concentration over time were associated with the absence of long-term symptoms.

Conclusions: Worse COVID-19 severity by 30 days was associated with higher early and post-acute period cytokine concentrations. Participants with long-term symptoms did not see resolution of cytokine responses over time.

Source: Mendall C, Li X, Pakanati V, Liu C, Wang T, Morelli D, Korpak A, Baraff A, Isaacs SN, Chang KM, Le E, Holodniy M, Sugimoto JD, Smith NL, Lee JS, Ross JM, Shah JA. Peripheral blood cytokines during early and post-acute stages of SARS-CoV-2 infection are associated with disease severity and long-term symptoms. Front Immunol. 2026 Jul 15;17:1870109. doi: 10.3389/fimmu.2026.1870109. PMID: 42528778; PMCID: PMC13415590. https://pmc.ncbi.nlm.nih.gov/articles/PMC13415590/ (Full text)

Altered TRPM3‐Dependent Cytosolic and Mitochondrial Calcium Influx in Natural Killer Cells of Post‐COVID‐19 Condition Patients

Abstract:

According to the World Health Organization (WHO), approximately 6% of COVID-19 cases develop serious long-term sequelae referred to as post-COVID-19 condition (PCC). Immunological disturbances such as persistent activation of immune cells and reduced cytotoxicity by natural killer (NK) cells are reported as key aspects in PCC.

Recently, electrophysiological studies by our group demonstrated impairment of transient receptor potential melastatin 3 (TRPM3) ion channels in NK cells from PCC patients. The significant reduction in TRPM3 channel function and reduced functional activity by NK cells warrants further investigation. Hence, using live cell calcium (Ca2+) imaging ex vivo, we examined the downstream impact of TRPM3 ion channel dysfunction on intracellular and mitochondrial Ca2+ mobilization in NK cells from N = 8 PCC patients, age and sex matched to N = 8 PCC healthy controls (HC).

Our findings provide new evidence of altered passive and TRPM3-mediated Ca2+ influx, significantly impacting cytoplasmic and mitochondrial Ca2+ mobilization in PCC. Passive cytosolic Ca2+ influx amplitude (p < 0.0001) was significantly reduced in PCC; however, passive mitochondrial Ca2+ mobilization (p < 0.0001) was significantly increased. Importantly, cytoplasmic and mitochondrial response rates (slope, p < 0.001) to pregnenolone sulphate stimulation were significantly reduced in PCC.

Consequently, TRPM3-dependent cytosolic (p < 0.001) and mitochondrial (p < 0.0005) Ca2+ mobilization were significantly reduced in PCC compared with HC. Altered ion channel Ca2+ signalling can severely impact both the immune system and bioenergetic processes, potentially leading to broader systemic dysregulations underpinning the pathomechanism of the PCC condition, and warrants further investigations.

Source: Magawa CT, Eaton-Fitch N, Muraki K, Marshall-Gradisnik S. Altered TRPM3-Dependent Cytosolic and Mitochondrial Calcium Influx in Natural Killer Cells of Post-COVID-19 Condition Patients. Eur J Immunol. 2026 Jul;56(7):e70240. doi: 10.1002/eji.70240. PMID: 42484498; PMCID: PMC13390657.  https://pmc.ncbi.nlm.nih.gov/articles/PMC13390657/ (Full text)

Central origin of fatigability in Myalgic encephalomyelitis/chronic fatigue syndrome revealed by multimodal neuroimaging

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating chronic disease characterized by physical and mental fatigue, post-exertional malaise, muscle pain, headaches, and unrefreshing sleep. Fatigability refers to a reduction of muscular force over time despite willed effort and has a central and a peripheral component. We studied whether fatigability in ME/CFS is related to central or peripheral mechanisms.

We recruited fifteen patients with ME/CFS and nineteen age- and sex-matched healthy volunteers (with seven females in each group). Participants performed a fatiguing grip force task, requiring them to maintain 50% of their maximum voluntary force during alternating 30 s blocks of grip and rest. We simultaneously recorded grip force, forearm muscle activity with electromyography, and brain activity with electroencephalography and functional magnetic resonance imaging. Fatigue onset was based on grip force performance and was set individually for each participant.

ME/CFS patients generated the same level of maximum voluntary force than healthy volunteers but developed fatigue much earlier. Healthy volunteers increased their muscle and brain activity from the beginning of the task until the onset of fatigue. Specifically, muscle activity shifted from high to low frequencies and brain activity increased steadily in cortical and subcortical areas. Then, muscle and brain activity declined slowly. In contrast, in ME/CFS, the muscles and brain activity only showed minimal fluctuations across all the task blocks.

The earlier onset of fatigue in ME/CFS is related to central mechanisms, as their brain did not increase its output to drive muscle activity like healthy volunteers did. While this is a small sample study, and caution should be taken regarding the generalizability of the results, the earlier onset of fatigue in ME/CFS was observed to be related to central mechanisms. The brain in ME/CFS participants did not increase its output to drive muscle activity like healthy volunteers did.

Source: Bedard P, Knutson KM, McGurrin PM, Vial F, Popa T, Horovitz SG, Hallett M, Nath A, Walitt B. Central origin of fatigability in Myalgic encephalomyelitis/chronic fatigue syndrome revealed by multimodal neuroimaging. Neuroimage Clin. 2026 Jul 28;51:104041. doi: 10.1016/j.nicl.2026.104041. Epub ahead of print. PMID: 42551185. https://www.sciencedirect.com/science/article/pii/S2213158226001002 (Full text)