Varicella Vaccine Reduces Herpes Zoster Morbidity in Older Adults

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Summary and Comment

Varicella Vaccine Reduces Herpes Zoster Morbidity in Older Adults

In a large trial among older adults, a new varicella vaccine significantly reduced morbidity from herpes zoster and postherpetic neuralgia.

Waning cell-mediated immunity to varicella-zoster virus (VZV) is associated with an increased incidence of herpes zoster in older individuals. In a prospective, multicenter, randomized, controlled trial that was partially supported by industry, investigators tested whether administration of a live attenuated VZV vaccine to older adults might boost their immunity against VZV and prevent the development of zoster.

From November 1998 through September 2001, 38,546 immunocompetent subjects $≥$ 60 years old received a single dose of VZV vaccine or placebo; follow-up continued through April 2004 (mean duration, 3.1 years). Compared with control subjects, vaccine recipients showed significant reductions in incidence (5.4 vs. 11.1 episodes per 1000 person-years, respectively), duration, and severity of herpes zoster, overall burden of illness from the condition, and incidence of postherpetic neuralgia (0.46 vs. 1.38 episodes per 1000 person-years). Side effects during the first 42 postimmunization days (mostly minor injection-site reactions) were more common in vaccine recipients than in controls (58% vs. 34%). Among the 957 participants who developed herpes zoster, PCR testing detected wild-type VZV DNA in 894 and vaccine-virus DNA in none.

Comment: Given the morbidity associated with herpes zoster, the VZV vaccine's ability to reduce disease incidence by >50% and postherpetic neuralgia incidence by 66.5% strongly suggests that it could produce a major benefit for older adults. As noted by an editorialist, vaccination would likely be quite cost-effective. The VZV vaccine employed in this trial was about 14-fold more potent than the preparation currently licensed for children, so this formulation will require FDA approval.

— Richard T. Ellison III, MD

Published in Journal Watch Infectious Diseases June 24, 2005