Oxman MN, Levin MH, Johnson GR, et al: A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults. N Engl J Med 2005;352(22):2271-84.
A million or more cases of herpes zoster occur each year in the United States. Older adults are more vulnerable to severe herpes zoster and postherpetic neuralgia due to age-associated waning of cell-mediated immunity. These authors report the results of a randomized double-blind placebo-controlled trial of an investigational live attenuated Oka/Merck varicella-zoster virus (VZV) vaccine in 38,546 adults 60 years of age or older. Because a high-potency vaccine is needed to boost T-cell response in older adults, the VZV vaccine is at least 14 times more potent than the vaccine currently licensed to prevent varicella. After about 3 years of surveillance, there were 315 cases of herpes zoster among vaccine recipients and 642 among placebo recipients. There were 27 cases of postherpetic neuralgia among vaccine recipients and 80 among placebo recipients. The vaccine reduced illness due to herpes zoster by 51.3% (P <0.001) and the incidence of postherpetic neuralgia by 66.5% (P <0.001). The vaccine did not induce herpes zoster. Vaccine recipients did report mild but more frequent reactions at the injection site compared to placebo recipients. Before this important vaccine can be licensed and used, more studies including some to determine duration of protection are needed.