E2 ModerateModerate confidencePEM unclearCross-SectionalPeer-reviewedMachine draft
Reactivation of herpesvirus type 6 and IgA/IgM-mediated responses to activin-A underpin long COVID, including affective symptoms and chronic fatigue syndrome.
Vojdani, Aristo, Almulla, Abbas F, Zhou, Bo et al. · Acta neuropsychiatrica · 2024 · DOI
Quick Summary
This study found that long COVID patients have higher levels of antibodies (immune proteins) against reactivated dormant viruses, particularly herpesvirus type 6, along with signs of ongoing inflammation and immune activation. The researchers identified a pattern of immune markers that correctly identified long COVID patients about 81% of the time, and similar patterns were linked to depression, anxiety, and fatigue symptoms. These findings suggest that viral reactivation combined with abnormal immune responses may drive long COVID and its associated mood and fatigue symptoms.
Why It Matters
This study provides potential biological markers that could help explain the mechanism of long COVID and its neuropsychiatric features, bridging the gap between infection and persistent symptoms. For ME/CFS patients, identifying HHV-6 reactivation and autoimmune responses offers testable hypotheses for why some patients develop chronic fatigue and mood disorders, potentially opening avenues for targeted immune or antiviral interventions.
Observed Findings
- Long COVID patients had significantly elevated IgG/IgM antibodies to SARS-CoV-2, HHV-6, and HHV-6-duTPase compared to controls.
- IgA and IgM antibodies to activin-A were significantly elevated in long COVID patients, suggesting an autoimmune component.
- Biomarkers of inflammation (CRP), oxidative stress (AOPP), and insulin resistance (HOMA2-IR) were all significantly elevated in long COVID.
- Neural network analysis identified a five-biomarker signature with 80.6% accuracy (78.9% sensitivity, 81.8% specificity) for long COVID diagnosis.
- Depressive/anxiety symptoms and chronic fatigue severity correlated most strongly with IgM-HHV-6-duTPase, IgG-HHV-6, and CRP.
Inferred Conclusions
- HHV-6 reactivation is a central feature of long COVID pathophysiology, acting alongside persistent SARS-CoV-2 infection.
- Autoimmune responses to activin-A (a cytokine regulating immune and metabolic function) may drive neuropsychiatric and fatigue symptoms in long COVID.
- Combined assessment of viral antibodies, autoimmune markers, and oxidative stress biomarkers may help identify and stratify long COVID patients for targeted intervention.
Remaining Questions
- Does HHV-6 reactivation precede long COVID symptom onset, or is it a consequence of immune dysregulation caused by SARS-CoV-2?
What This Study Does Not Prove
This study does not prove that HHV-6 reactivation or activin-A antibodies *cause* long COVID—it only shows associations in a snapshot in time. Cross-sectional design cannot establish whether immune marker elevations precede symptom onset, persist longitudinally, or change with treatment. The study also does not demonstrate whether these markers are specific to long COVID or overlap with other post-viral conditions.
Tags
Symptom:Cognitive DysfunctionFatigue
Biomarker:CytokinesAutoantibodiesBlood Biomarker
Phenotype:Infection-TriggeredLong COVID Overlap
Method Flag:Weak Case DefinitionExploratory OnlyMixed Cohort
Metadata
- DOI
- 10.1017/neu.2024.10
- PMID
- 38571295
- Review status
- Machine draft
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 8 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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