Tag: long Covid

Functional olfactory impairment and fatigue in post-COVID-19 syndrome including ME/CFS – a longitudinal prospective observational study

Abstract:

Post-COVID-19 syndrome (PCS) affects a significant proportion of individuals, with olfactory impairment and fatigue as prominent long-term symptoms. A subset of PCS patients with pronounced fatigue meets the diagnostic criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), here referred to as PCS-ME/CFS. This study explores the relationship between PCS, fatigue, and olfactory function, and investigates the potential of olfactory impairment as a diagnostic and prognostic marker.

We assessed olfactory function up to 28 months post-COVID-19 in 45 PCS patients (22 PCS, 23 PCS-ME/CFS) using the extended Sniffin’ Sticks test, which evaluates odor threshold, discrimination, and identification, providing a composite score. Fatigue severity and health-related quality of life were assessed using validated questionnaires, a standardized test measured cognitive function, and handgrip strength indicated physical fatiguability. Both PCS and PCS-ME/CFS patients showed significant improvement in olfactory function, with all patients returning to normosmia after 20 months, regardless of diagnosis.

While odor threshold was the most affected olfactory measure in Sniffin’ Sticks testing, odor identification was the only measure that remained impaired over time. Olfactory impairment correlated with cognitive, physical, and mental performance, with stronger correlations in the PCS group, particularly linking better odor discrimination at baseline to improved daily functioning and health-related quality of life after 20 months.

Our findings suggest that odor identification assessed in standardized testing may remain impaired the longest in patients with persisting symptoms after COVID-19, reflecting persisting central processing difficulties. Correlations between olfactory performance, cognitive function, and physical ability point to shared underlying mechanisms. Early olfactory improvements may be linked to better long-term cognitive outcomes, highlighting a possible prognostic role of olfactory function in these patients.

Source: Meyer-Arndt L, Pierchalla G, Mödl L, Wohlrab F, Legler F, Hoppmann U, Kedor C, Wittke K, Freitag H, Konietschke F, Olze H, Paul F, Scheibenbogen C, Bellmann-Strobl J, Förster-Ruhrmann U. Functional olfactory impairment and fatigue in post-COVID-19 syndrome including ME/CFS – a longitudinal prospective observational study. Brain Behav Immun Health. 2025 Oct 14;50:101124. doi: 10.1016/j.bbih.2025.101124. PMID: 41281896; PMCID: PMC12634829. https://pmc.ncbi.nlm.nih.gov/articles/PMC12634829/ (Full text)

Urinary Peptidomic Profiling In Post-Acute Sequelae of SARS-CoV-2 Infection: A Case-Control Study

Abstract:

Post-acute sequelae of severe acute respiratory syndrome coronavirus 2-infection (PASC) is challenging to diagnose and treat, and its molecular pathophysiology remains unclear. Urinary peptidomics can provide valuable information on urine peptides that may enable improved and specified PASC diagnosis.
Using standardized capillary electrophoresis-MS, we examined the urinary peptidomes of 50 patients with PASC 10 months after COVID-19 and 50 controls, including healthy individuals (n = 42) and patients with non-COVID-19-associated myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) (n = 8).Based on peptide abundance differences between cases and controls, we developed a diagnostic model using a support vector machine. The abundance of 195 urine peptides among PASC patients significantly differed from that in controls, with a predominant abundance of collagen alpha chains. This molecular signature (PASC195) effectively distinguished PASC cases from controls in the training set (AUC of 0.949 [95% CI 0.900–0.998; p < 0.0001]) and independent validation set (AUC of 0.962 [95% CI 0.897–1.00]; p < 0.0001]). In silico assessment suggested exercise, GLP-1RAs and mineralocorticoid receptor antagonists (MRAs) as potentially efficacious interventions. We present a novel and non-invasive diagnostic model for PASC. Reflecting its molecular pathophysiology, PASC195 has the potential to advance diagnostics and inform therapeutic interventions.

Statement of Significance of the Study

Despite the recent emergence of omics-derived candidates for post-acute sequelae of SARS-CoV-2 infection (PASC), the pending validation of proposed markers and lack of consensus result in the continuous reliance on symptom-based criteria, being subject to diagnostic uncertainties and potential recall bias. Building upon prior findings of renal involvement in acute COVID-19 pathophysiology and PASC-associated alterations, we hypothesized that the use of urinary peptides for PASC-specific biomarker discovery, unlike conventional specimens that have been utilized thus far, may offer complementary information on putative disease mechanisms.

In the present study, 195 significantly expressed peptides were used to form a classifier termed PASC195, which effectively discriminated PASC from non-PASC (p < 0.0001), including healthy individuals and non-COVID-19-associated myalgic encephalomyelitis/chronic fatigue syndrome, in both the derivation (n = 60) and an independent validation set (n = 40). The peptidome profile associated with PASC was consistent with a shift in collagen turnover, with most PASC195 peptides derived from alpha chains. Ongoing inflammatory responses, hemostatic imbalances, and endothelial damage were indicated by cross-sectional variations in endogenous peptide excretion.

Source: Gülmez D, Siwy J, Kurz K, Wendt R, Banasik M, Peters B, Dudoignon E, Depret F, Salgueira M, Nowacki E, Kurnikowski A, Mussnig S, Krenn S, Gonos S, Löffler-Ragg J, Weiss G, Mischak H, Hecking M, Schernhammer E, Beige J; UriCoV Working Group. Urinary Peptidomic Profiling In Post-Acute Sequelae of SARS-CoV-2 Infection: A Case-Control Study. Proteomics. 2025 Nov 21:e70074. doi: 10.1002/pmic.70074. Epub ahead of print. PMID: 41273049. https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/pmic.70074 (Full text)

Healthcare Situation of 3,345 Long COVID Patients in Germany: Results of a Nationwide Survey

Abstract:

Long COVID includes persistent symptoms after SARS CoV 2 infection and leads to multiple physical and psychosocial burdens.Between March and April 2025, a nationwide sample of long COVID patients was recruited by means of an anonymous online survey. Demographic parameters, symptoms, use of outpatient/inpatient care services and subjective satisfaction with care were recorded.

In total, 3345 people (average age 49 ± 13 years; 81.5% women) completed the survey. 83.8% reported a medically confirmed long COVID diagnosis, with a further 12.2% reporting a post-vac syndrome. The average duration of symptoms was 2.8 ± 1.1 years, with only 36.4% reporting an improvement in their symptoms over time. Almost nine out of ten patients (89.1%) were on long-term sick leave (average 1.8 ± 1.3 years), 70.8% reported total or partial incapacity for work and 46.4% applied for a pension. General practitioner care was the first point of contact for 75.7%. Over the course of the illness, 93% consulted more than three and 21.5% more than ten different doctors. Personal financial contributions were high: 41.4% invested more than € 1,000 and 11.3% more than € 10,000 in diagnostics or therapy. 60% received a rehabilitation intervention. Overall, 97.2% rated their care as “poor” or “very poor”.

This survey highlights a high and persistent burden among long COVID patients, as well as significant socioeconomic consequences, accompanied by a predominantly negative evaluation of the current care situation. Improvements require structured, easily accessible, and cross-sectoral services. Improving the primary care system, establishing clear referral pathways, and (where clinically indicated) integrating rehabilitative interventions into an interdisciplinary care concept could help to improve the care situation of patients with long COVID.

Source: Gloeckl R, Rischer R, Schneeberger T, Jarosch I, Blome C, Koczulla R. Versorgungssituation von 3345 Long-COVID-Betroffenen in Deutschland: Ergebnisse einer bundesweiten Befragung [Healthcare Situation of 3,345 Long COVID Patients in Germany: Results of a Nationwide Survey]. Pneumologie. 2025 Nov 11. German. doi: 10.1055/a-2725-5650. Epub ahead of print. PMID: 41218624. https://pubmed.ncbi.nlm.nih.gov/41218624/  https://www.thieme-connect.de/products/ejournals/html/10.1055/a-2725-5650 (Full text available in German]

Integrated immune, hormonal, and transcriptomic profiling reveals sex-specific dysregulation in long COVID patients with ME/CFS

Abstract:

Long COVID (LC) manifests with sex-specific differences, particularly in those with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Our study reveals that female LC patients (LCF) with ME/CFS show a shift toward myelopoiesis, reduced lymphocytes, increased neutrophils/monocytes, and depleted regulatory T cells-suggesting persistent immune activation. Elevated CD71+ erythroid cells and disrupted erythropoiesis contribute to fatigue and tissue damage in LCF.

Cytokine profiling indicates a stronger pro-inflammatory response in LCF compared to males (LCM), along with markers of gut barrier dysfunction. Hormonal analysis shows reduced testosterone in LCF and estradiol in LCM. Transcriptomic data reveal neuroinflammatory signatures in LCF, potentially explaining cognitive symptoms. We also identify biomarkers that distinguish LCF from LCM and correlate with sex-specific clinical symptoms.

Overall, LC with ME/CFS is characterized by sex-specific immune, hormonal, and transcriptional alterations, with females exhibiting more severe inflammation. These insights underscore the need for sex-tailored interventions, including consideration of hormone replacement therapy.

Source: Shahbaz S, Osman M, Syed H, Mason A, Rosychuk RJ, Cohen Tervaert JW, Elahi S. Integrated immune, hormonal, and transcriptomic profiling reveals sex-specific dysregulation in long COVID patients with ME/CFS. Cell Rep Med. 2025 Nov 7:102449. doi: 10.1016/j.xcrm.2025.102449. Epub ahead of print. PMID: 41205594. https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(25)00522-1 (Full text)

Severe COVID-19 induces prolonged elevation of the acute-phase protein pentraxin 3

Abstract:

Introduction: During the acute-phase of COVID-19, elevated levels of several acute-phase proteins, such as C-reactive protein (CRP), mannose-binding lectin (MBL), pentraxin 3 (PTX-3), serum amyloid A (SAA) and surfactant protein D (SP-D), are associated with severe to fatal clinical outcomes. Typically, these markers return to baseline within days after resolution of the acute infection.

Methods: In this study, we assessed the plasma levels of these proteins in a well-defined cohort of 141 COVID-19 convalescent patients 10 weeks after infection and compared them to 98 non-infected controls. In addition, we performed genetic analyses in a subgroup of patients and related the findings with structural equation modelling to disease severity.

Results: In contrast to other acute-phase proteins, PTX-3 levels were significantly higher in severe COVID-19 convalescent patients than in the control group. Furthermore, a higher proportion of patients with severe COVID-19 exhibited PTX-3 levels above 5000 pg/ml even 10 months post-infection, compared to those with mild disease. To explore potential genetic influences, a genetic analysis was performed on all severely affected patients (n=36) and on an age- and sex-matched subset of mild COVID-19 patients (n=38). Results revealed a significantly higher frequency (p<0.0001) of the homozygous wildtype genotype of the PTX-3 SNP rs971145291 in severe (15 out of 36) versus mild (1 out of 38) COVID-19 patients. Using structural equation modelling, the association of this PTX-3 genotype and disease severity was shown to be mediated by elevated PTX-3 levels, with no contribution from other analyzed (clinical) confounders.

Discussion: In summary, severe COVID-19 patients show high PTX-3 serum levels which may be influenced by genetic predisposition, specifically the absence of the rs971145291 SNP variant. PTX-3 may thus serve both as a biomarker for tissue damage and/or long-term immune activation and eventually post-COVID-19 complications.

Source: Kratzer B, Stieger RB, Durmus S, Trapin D, Gattinger P, Ettel P, Sehgal ANA, Borochova K, Dorofeeva Y, Tulaeva I, Grabmeier-Pfistershammer K, Tauber PA, Gerdov M, Perkmann T, Fae I, Wenda S, Kundi M, Wrighton S, Fischer GF, Valenta R, Pickl WF. Severe COVID-19 induces prolonged elevation of the acute-phase protein pentraxin 3. Front Immunol. 2025 Oct 1;16:1672485. doi: 10.3389/fimmu.2025.1672485. PMID: 41103408; PMCID: PMC12520919. https://pmc.ncbi.nlm.nih.gov/articles/PMC12520919/ (Full text)

Post-Exertional Symptom Exacerbation after Sub-Maximal Exercise in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-Acute Sequelae of COVID-19

Abstract:

Purpose: In individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-acute sequelae of SARS-CoV-2 infection (PASC), physical activity can exacerbate symptoms for days-to-weeks, referred to as post-exertional symptom exacerbation (PESE). This study characterized the trajectory of PESE symptoms before and for 7 days after a sub-maximal exercise task in individuals with ME/CFS or PASC.

Methods: Individuals with ME/CFS (n=30) or PASC (n=30) and matched controls (n=30) were recruited from a university hospital and the community setting. Participants completed a 25-minute moderate intensity exercise on a whole-body cycle ergometer. The trajectory of 8 commonly reported PESE symptoms (physical fatigue, mental fatigue, pain, physical function, flu-like symptoms, gastrointestinal symptoms, sleep dysfunction, anxiety) before and for 7 days after exercise.

Results: There was variability in the proportion of those who experienced increased symptoms ranging from 46/60 reporting physical fatigue to only 18/30 reporting anxiety. There was no change in any of the symptoms across the 7-day period when analyzed individually. An aggregate score of 4-5 symptoms that includes physical fatigue, mental fatigue, physical function and flu-like symptoms, with or without pain, was more comprehensive in capturing maximal changes in PESE. Changes were greatest during the 72h post-exercise and for those with ME/CFS. The aggregate score shows 8/30 of individuals with ME/CFS and 12/30 with PASC show minimal-to-no increase in PESE, while 6-7/30 show increases greater than 3/10 points.

Conclusions: PESE to a clinically relevant exercise task is variable in individuals with ME/CFS and PASC as submaximal exercise does not exacerbate symptoms for some, while modifications of intensity may be necessary to minimize PESE in others.

Source: Berardi G, Janowski A, McNally S, Post A, Garg A, Sluka KA. Post-Exertional Symptom Exacerbation after Sub-Maximal Exercise in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-Acute Sequelae of COVID-19. Med Sci Sports Exerc. 2025 Nov 4. doi: 10.1249/MSS.0000000000003891. Epub ahead of print. PMID: 41185151. https://pubmed.ncbi.nlm.nih.gov/41185151/

Autonomic phenotyping, brain blood flow control, and cognitive-motor-integration in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome: A pilot study

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and the prolonged sequelae after COVID-19 (>3 months; Long COVID) have similar symptomology, are both associated with autonomic dysfunction, and a growing proportion of Long COVID patients are developing ME/CFS. We aimed to determine an autonomic phenotype of patients with ME/CFS vs Long COVID. We hypothesized that the groups would differ from controls yet be similar to one another.

We recruited sedentary controls (n = 10), mild/moderate ME/CFS patients (n = 12), and Long COVID patients (n = 9) to undergo 1) breathing 5 % CO2, 2) breathing 10 % O2, and 3) 5-minutes of 70° head-up tilt. Respiratory, hemodynamic, and cerebrovascular variables were measured throughout the 3 trials. Resting vascular function and cognitive-motor-integration were also assessed. ME/CFS and Long COVID were similar to the healthy controls and each other with regard to resting vascular function and the hemodynamic responses to hypoxia, hypercapnia, and head-up tilt (p > 0.05). However, in ME/CFS we observed a greater reduction of cerebrovascular resistance (p = 0.041) and impaired autoregulation (p = 0.042) during hypercapnia alongside impaired cognitive-motor integration (p < 0.02), and in Long COVID we observed reduced peripheral and end-tidal oxygen (p < 0.04) and less vagal withdrawal during tilt (p = 0.028).

Our findings suggest unique phenotypes when comparing ME/CFS and Long COVID whereby we have shown that Long COVID patients experience hypoxia while upright contributing to less vagal withdrawal, and ME/CFS patients experience impaired cerebrovascular control during potentially leading to reduced cognitive-motor integration. These differences could stem from disease severity/duration or some unique aspect of the COVID-19 virus.

Source: Badhwar S, Pereira TJ, Kerr K, Bray R, Tabassum F, Sergio L, Edgell H. Autonomic phenotyping, brain blood flow control, and cognitive-motor-integration in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome: A pilot study. Auton Neurosci. 2025 Oct 14;262:103358. doi: 10.1016/j.autneu.2025.103358. Epub ahead of print. PMID: 41138391. https://www.autonomicneuroscience.com/article/S1566-0702(25)00120-1/fulltext (Full text)

HLA and pathogens in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and other post-infection conditions

Abstract:

Viral infections have been widely implicated in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) pathogenesis. Recent evidence has also identified certain Human Leukocyte Antigen (HLA) alleles that are significantly associated with ME/CFS risk/protection. Here we tested the hypothesis that ME/CFS risk or protection conferred from those HLA alleles is associated with binding affinity to antigens of HHV viruses, a critical step in initiating the adaptive immune system response to foreign antigens.

Specifically, we determined in silico the predicted binding affinity of two susceptibility alleles (C*07:04, DQB1*03:03) and two protective alleles (B*08:01, DPB1*02:01) to > 10,000 antigens of the 9 Human Herpes Viruses (HHV1, HHV2, HHV3, HHV4, HHV5, HHV6A, HHV6B, HHV7, HHV8) which have been implicated in the etiology of ME/CFS. We found that the binding affinity of all HHV antigens to the susceptibility alleles was significantly weaker than the binding affinity to the protective alleles (P < 0.001). In fact, none of the HHV antigens showed strong binding to the susceptibility alleles, in contrast to the strong bindings showed by the protective alleles. These findings are in keeping with the hypothesis that the effect of a putative HHV insult in contributing to ME/CFS is modulated by the host’s HLA immunogenetic makeup.

We speculate that strong HLA-antigen binding likely protects against ME/CFS via elimination of virus antigens; conversely, weak HLA-antigen binding may permit persistence of foreign antigens, contributing to ME/CFS and other chronic conditions. Finally, with respect to the latter, we determined the binding affinities to the 4 HLA alleles above to pathogens causing two chronic diseases with very similar symptomatology to ME/CFS, namely Long COVID and post-treatment Lyme disease syndrome (PTLDS).

We found that the 2 ME/CFS susceptibility HLA alleles above had very weak binding with SARS-CoV-2 virus glycoprotein (involved in Long COVID) and 5 proteins of Borrelia burgdorferi (involved in PTLDS), in contrast to the ME/CFS protective alleles that showed strong bindings. These findings support the hypothesis that ME/CFS, long COVID and PTLDS are caused by persistent pathogenic antigens that could not be eliminated due to inadequate protection by the patient’s HLA makeup.

Source: Georgopoulos AP, James LM, Peterson PK. HLA and pathogens in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and other post-infection conditions. Sci Rep. 2025 Oct 24;15(1):37303. doi: 10.1038/s41598-025-21230-z. PMID: 41136524. https://www.nature.com/articles/s41598-025-21230-z (Full text)

Corticosteroids with low glucocorticoid activity as a potential therapeutic strategy for post-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome in patients with bipolar affective disorder: A case report

Abstract:

Background: The COVID-19 pandemic has led to an increase in post-acute sequelae, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), potentially mediated by dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis. Corticosteroids are occasionally administered to ameliorate fatigue symptoms in ME/CFS; however, their psychiatric adverse effects, particularly in individuals with preexisting mood disorders, necessitate careful consideration.

Case presentation: We report the case of a 32-year-old woman with bipolar disorder who developed ME/CFS following COVID-19 infection. Initial corticosteroid therapy with betamethasone and prednisolone, agents with potent glucocorticoid receptor (GR) activity, resulted in a manic episode with psychotic features, necessitating psychiatric hospitalization. Although mood stabilization was achieved with olanzapine and valproate, corticosteroid withdrawal subsequently led to metabolic alkalosis and hypoxemia, secondary to hypothalamic hypoadrenalism. Following a comprehensive endocrinological assessment, physiological replacement therapy with hydrocortisone, characterized by relatively higher mineralocorticoid receptor (MR) activity and lower GR potency, was initiated, resulting in the resolution of physical symptoms without destabilization of psychiatric status.

Conclusion: The clinical course suggests that GR-dominant corticosteroids may exacerbate psychiatric instability in patients with mood disorders. Simultaneously, MR-favoring agents, such as hydrocortisone, may offer a safer therapeutic alternative for managing HPA axis dysfunction. This case underscores the critical role of receptor selectivity in corticosteroid therapy, particularly in patients with comorbid psychiatric conditions, and highlights the necessity for individualized treatment strategies that integrate both endocrine and neuropsychiatric considerations.

Source: Nakajima K, Ayani N, Matsuoka T, Kasahara K, Nakajima Y, Ikawa H, Kitaoka R, Akimoto T, Narumoto J. Corticosteroids with low glucocorticoid activity as a potential therapeutic strategy for post-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome in patients with bipolar affective disorder: A case report. PCN Rep. 2025 Oct 12;4(4):e70222. doi: 10.1002/pcn5.70222. PMID: 41089430; PMCID: PMC12515714.

Pacing with a heart rate monitor for people with myalgic encephalomyelitis/chronic fatigue syndrome and long COVID: a feasibility study

Abstract:

Background: People living with ME/CFS and LC frequently live with post-exertional malaise (PEM), which is associated with impairments in aerobic metabolism. They often use pacing with a heart rate monitor (HRM) to minimize time spent above the anaerobic threshold; however, there is limited research on the feasibility and efficacy.

Objective: To establish the acceptability, adherence, outcomes, and adverse events associated with pacing with an HRM for a future definitive study.

Methods: After informed consent and baseline measurements (including 10 min stand test, 5 questionnaires, accelerometry, heart rate variability, and lactate), participants were randomized into a control or intervention group using simple randomization and sealed envelopes. The intervention group used a heart rate monitor with weekly online HRM pacing advice (how to use the HRM, problem solving), and the control group received weekly online pacing advice (how to pace, problem solving). Follow-up measures were repeated, and semi-structured interviews were conducted at two and six months post-enrolment.

Results: 47 participants were recruited; however, recruiting people with LC was difficult due to wanting to use/already using HR monitoring. The interviews identified that the procedure was acceptable, and the majority of the participants completed the outcome measures. There were some changes from baseline to follow-up in all the outcome measures except the 10-minute stand test and accelerometry. There were no serious adverse events. Follow-up interviews identified 89% continued using HRM at 8 weeks and 66% after 6 months.

Conclusions: Studies of HRM are feasible and acceptable for ME/CFS and LC, although recruitment strategies should be reviewed for LC.

Clinical Trial registration number: ISRCTN10554129.

Source: Clague-Baker, N., Davenport, T. E., Wickens, B., Leeming, H., Dickinson, K., McBurney, E., … Hilliard, N. (2025). Pacing with a heart rate monitor for people with myalgic encephalomyelitis/chronic fatigue syndrome and long COVID: a feasibility study. Fatigue: Biomedicine, Health &amp; Behavior, 1–23. https://doi.org/10.1080/21641846.2025.2565103 https://www.tandfonline.com/doi/full/10.1080/21641846.2025.2565103#abstract (Full text)