Every week, we scan PubMed and ClinicalTrials.gov for the latest research on long COVID, ME/CFS, chronic Lyme, and viral persistence — and deliver an editorial summary of what matters most.
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Two studies this week reinforce something researchers have been circling for years: post-infection conditions share more biology than their separate diagnostic labels suggest. A Norwegian group published the most convincing ME/CFS biomarker panel yet, identifying a cluster of immune exhaustion markers that distinguish the condition from major depression with over 90% accuracy. What makes their work especially interesting is the overlap — several of those same markers show up in long COVID cohorts and in patients with reactivated EBV, suggesting a common pathway of immune dysfunction across these conditions rather than three separate diseases.
Meanwhile, a team at Stanford found that EBV reactivation during acute COVID predicted neurological symptoms lasting well beyond viral clearance. The implication isn't that EBV causes long COVID in every case, but that latent viruses may be waking up during immune disruption and driving symptoms on their own. For the trial-minded, a low-dose naltrexone study focused specifically on post-infection fatigue is now enrolling — one of the first to include both long COVID and ME/CFS patients in the same cohort.
Brain, Behavior, and Immunity, 2026 · Fluge Ø, Rekeland I et al.
A panel of immune exhaustion markers — including elevated PD-1 on CD8+ T cells, reduced NK cell cytotoxicity, and specific cytokine ratios — correctly identified ME/CFS patients versus depressed controls with 91% sensitivity. Several of these markers overlap with those found in long COVID and post-EBV cohorts, suggesting shared immune mechanisms.
Researchers at Haukeland University Hospital analyzed immune cell phenotyping and serum cytokine profiles in 214 ME/CFS patients, 98 patients with major depressive disorder, and 120 healthy controls. The ME/CFS group showed a distinct signature of T-cell exhaustion and impaired innate immune function that was absent in depression, even when fatigue severity scores were comparable between the two groups. The panel held up in a validation cohort of 80 additional patients.
Nature Immunology, 2026 · Peluso MJ, Henrich TJ et al.
Patients who showed EBV reactivation during acute COVID were three times more likely to develop persistent brain fog and neuropathy at 12 months. The finding suggests that latent herpesvirus reactivation — not just SARS-CoV-2 itself — may be driving a subset of long-term neurological symptoms.
A Stanford-led longitudinal study followed 340 COVID patients from acute infection through 12 months of recovery. Those with serological evidence of EBV reactivation (elevated early antigen IgG) during the first two weeks of illness had significantly higher rates of cognitive impairment, peripheral neuropathy, and headache at one year compared to those without reactivation, even after adjusting for COVID severity, age, and vaccination status.
This randomized, placebo-controlled trial tests whether low-dose naltrexone (4.5 mg daily) reduces fatigue severity in patients with post-infection fatigue from long COVID or ME/CFS. The primary outcome is the Chalder Fatigue Scale at 16 weeks, with secondary endpoints including PET-measured neuroinflammation, six-minute walk distance, and patient-reported cognitive function. The trial runs 16 weeks with an optional open-label extension.