A potent live zoster vaccine halved the incidence of herpes zoster and reduced its disease burden and complications even more dramatically in a large study of adults aged 60 years and older, said M.N. Oxman, M.D., of the University of California, San Diego, and associates in the Shingles Prevention Study Group.
The investigators reported that an experimental vaccine about 14 times more potent than the Varivax varicella vaccine reduced the burden of illness from herpes zoster by 61.1% and reduced the incidence of postherpetic neuralgia by 66.5% in the older adults studied.
About 1 million cases of herpes zoster occur in the United States annually, causing profound pain and substantial morbidity, especially among patients who go on to develop postherpetic neuralgia, a complication that may last for years.
Older adults, a fast-growing population in the United States, are the population most susceptible to the disease, which is believed to be associated with an age-related decline in cell-mediated immunity to latent varicella-zoster virus (N. Engl. J. Med. 2005;352:2271–80).
A total of 957 confirmed cases of herpes zoster occurred in the 38,546 adults enrolled in the study at 22 Veterans Administration medical center sites: 315 in subjects who received the live-attenuated Oka/Merck VZV virus vaccine and 642 among those who received placebo.
Postherpetic neuralgia was diagnosed in 27 recipients of the vaccine and 80 placebo recipients in the study.
Subjects who received the vaccine and did become ill with herpes zoster over a median surveillance period of just over 3 years had less severe symptoms and had them for a shorter period of time than did those who received placebo.
Adverse reactions to the vaccine were mostly mild, and included erythema, pain and tenderness, and swelling at the injection site. No subjects were hospitalized for any event thought to be related to the vaccine.
In an accompanying editorial, Donald H. Gilden, M.D., called on the Food and Drug Administration to license the vaccine and study patients carefully, rather than subjecting it to a decade of further research in another large, confirmatory trial.
“The results are impressive,” wrote Dr. Gilden, professor and chairman of neurology and professor of microbiology at the University of Colorado Health Sciences Center, Denver, in an editorial (N. Engl. J. Med. 2005;352:2344–8).
“In fact, the high incidence of zoster found in the placebo group in the Shingles Prevention Study points to an urgent need for effective therapy.
“Although oral antiviral therapy shortens the duration of zoster and analgesic medications provide some relief of pain, 'an ounce of prevention'” struck Dr. Gilden as a prudent step, using a vaccine that “appears to be safe and effective clinically.”