The same vaccine that prevents chicken pox in children also prevents shingles, a skin disorder that causes painful lesions typically in elderly adults, according to new findings from a national study.
Shingles, or herpes zoster, is caused by the varicella virus, the same culprit behind chicken pox, once an itchy hallmark of childhood. Varicella remains in the body after the pox disappear, lying dormant in nerve cells. Scientists suspect that routine exposure to varicella--through contact with people with chicken pox--boosts the immune system and keeps the virus at bay. But with chicken pox at an all-time low (thanks to a new chicken pox vaccine approved by the FDA in 1995) adults' exposure to varicella is limited. Some scientists and physicians predict that as the Baby Boomer population ages, the cases of shingles could skyrocket.
A team of researchers led by Michael Oxman, a virologist with the University of California, San Diego, and the Veterans Affairs San Diego Healthcare System, developed a study of the varicella vaccine to see if it would prevent shingles as effectively as it prevents chicken pox. Between 1998 and 2001, 38,546 adults were enrolled at 22 sites around the country and followed for an average of 3 years. Scientists gave half a placebo and half a more-potent version of the chicken pox vaccine, developed by Merck. The vaccine reduced the incidence of shingles by 63.9% in people age 60 to 69 and 37.6% in people over 70. The incidence of postherpetic neuralgia--a severe complication of shingles--decreased 66.5% in all patients, the researchers report 2 June in the New England Journal of Medicine.
"This paper clearly indicates that varicella vaccine is useful for the prevention of herpes zoster," says Michiaki Takahashi, the Japanese scientist who invented the original varicella vaccine in 1974, which was licensed by Merck in 1980 and approved for use in the U.S. in 1995. It could be some time, however, before patients reap the benefits of the study. The vaccine used in the trial is at least 14 times more potent than the vaccine for chicken pox. Although the study found the high-potency dosage safe for patients, Merck would need to seek FDA approval for a new vaccine, which could take years.