Lerner, A Martin, Beqaj, Safedin H, Deeter, Robert G et al. · Drugs of today (Barcelona, Spain : 1998) · 2002 · DOI
This small study tested whether an antiviral medication called valacyclovir could help ME/CFS patients who had persistent Epstein-Barr virus (EBV) infection. Researchers gave 25 patients valacyclovir for 6 months and found that those with only EBV infection showed improvement in heart function and energy levels, but those with both EBV and cytomegalovirus infections did not improve.
This study suggests that viral serology may identify ME/CFS subsets with different treatment responses, and provides preliminary evidence that EBV-driven cardiac dysfunction in a subset of patients may be reversible with targeted antiviral therapy. These findings could help guide larger controlled trials examining mechanism-based stratification and treatment in ME/CFS.
This study does not prove valacyclovir is effective for ME/CFS broadly, as it was small, uncontrolled, and unblinded, making it vulnerable to placebo effect and reporting bias. It does not establish that EBV causes ME/CFS or that viral reactivation is the primary driver of disease in all patients. The absence of a placebo control group means improvement cannot be definitively attributed to the drug rather than natural recovery or expectancy effects.
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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