Lerner, A Martin, Beqaj, Safedin H, Deeter, Robert G et al. · In vivo (Athens, Greece) · 2007
This study tested whether the antiviral drug valacyclovir could help ME/CFS patients who had evidence of active Epstein-Barr virus (EBV) infection. Patients taking valacyclovir showed slightly larger improvements in physical energy and activity levels compared to those taking placebo over 6 months, and these gains continued over 3 years of follow-up. Heart rhythm problems also improved, and markers of active EBV infection decreased in the blood.
This study provides preliminary evidence that active EBV replication may contribute to ME/CFS symptoms in a subset of patients and that antiviral treatment targeting this subset could produce measurable improvements in physical function and cardiac parameters. If validated in larger trials, this could support the development of a mechanistic subtype classification for ME/CFS and personalized treatment strategies.
This study does not prove that EBV causes ME/CFS in all patients or that valacyclovir is effective as a general ME/CFS treatment—only in patients with serological evidence of active EBV infection. The small sample size and lack of reported statistical significance testing limit generalizability, and improvement does not establish causation; improvement could reflect natural recovery, placebo effects, or time-dependent factors rather than antiviral action alone.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Lerner, A Martin, Beqaj, Safedin H, Deeter, Robert G, & Fitzgerald, James T (2007). Valacyclovir treatment in Epstein-Barr virus subset chronic fatigue syndrome: thirty-six months follow-up.. In vivo (Athens, Greece). https://pubmed.ncbi.nlm.nih.gov/18019402/
BibTeX
@article{mecfsatlas-lerner-2007-valacyclovir-treatment,
author = {Lerner, A Martin and Beqaj, Safedin H and Deeter, Robert G and Fitzgerald, James T},
title = {Valacyclovir treatment in Epstein-Barr virus subset chronic fatigue syndrome: thirty-six months follow-up.},
journal = {In vivo (Athens, Greece)},
year = {2007},
note = {PubMed: 18019402},
url = {https://www.mecfsatlas.com/evidence/lerner-2007-valacyclovir-treatment},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/lerner-2007-valacyclovir-treatment
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