Background: Herpes zoster (HZ) and postherpetic neuralgia (PHN) cause significant morbidity in older adults. The incidence and severity of HZ and PHN increase with age in association with an age-related decline in varicella-zoster virus (VZV)-specific cell-mediated immunity (VZV-CMI). VZV vaccines can boost VZV-CMI. Therefore, we tested the hypothesis that VZV vaccination would protect older adults against HZ and PHN.
Methods: We enrolled 38,546 adults > or =60 years of age in a randomized, double-blind, placebo-controlled trial of an investigational HZ vaccine and actively followed subjects for the development of HZ. The primary end point was the burden of illness due to HZ (HZ BOI), a composite measure of the incidence, severity, and duration of pain and discomfort caused by HZ. The secondary end point was the incidence of PHN.
Results: Subject retention was >95%. HZ vaccine reduced the HZ BOI by 61.1% (95% confidence interval [CI], 51.1%-69.1%; P<.001) and reduced the incidence of PHN by 66.5% (95% CI, 47.5%-79.2%; P<.001). The incidence of HZ was also reduced by 51.3% (95% CI, 44.2%-57.6%; P<.001). HZ vaccine was well tolerated; injection site reactions were generally mild. HZ vaccine neither caused nor induced HZ.
Conclusion: The Shingles Prevention Study demonstrated that HZ vaccine significantly reduced the morbidity due to HZ and PHN in older adults.