June 3, 2005

Vaccine shows promise in preventing shingles

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Lawrence Marnett, Ph.D.

Vaccine shows promise in preventing shingles

An experimental vaccine cut in half the incidence of shingles, a painful and often-debilitating viral condition that afflicts many elderly people, a nationwide study has found.

The multi-center study, which included Vanderbilt University Medical Center, followed more than 38,500 people age 60 and older for an average of more than three years. The vaccine was designed to boost immunity against the varicella-zoster virus, which also causes chickenpox in children.

Compared with controls, people who received the vaccine were 51 percent less likely to develop shingles and 66 percent less likely to develop postherpetic neuralgia, often severe and persistent nerve pain that can follow the blistering shingles rash.

“This is a pivotal study,” said Peter F. Wright, M.D., director of the Division of Pediatric Infectious Diseases, who, with Marie R. Griffin, M.D., MPH, professor of Preventive Medicine and Medicine, enrolled and studied 1,800 people in the Vanderbilt part of the study.

The findings of the so-called Shingles Prevention Study were published in the June 2 New England Journal of Medicine.

The next step, said Wright, is for the manufacturer, Merck and Co. Inc., to obtain FDA approval to market the vaccine as a way to prevent shingles in the elderly.

According to the researchers, more than a million new cases of shingles, also called herpes zoster, occur in the United States each year.

Based on the findings of the study, people age 60 and older have a one in 40 chance of developing shingles. By age 85, the incidence rises to 50 percent. More than 10 percent of people with shingles experience postherpetic neuralgia.

Shingles is caused by the reactivation of the varicella-zoster virus, which persists in a dormant state in the nerve cells of people who had chickenpox as children. It is thought to result from a decline in immunity as people grow older.

The vaccine contains a live but weakened form of the varicella-zoster virus. It is a higher potency version of the vaccine that has been given to children to prevent chickenpox since 1995.

Half of the subjects in the study received the placebo, and the other half received a single injection of the vaccine.

The theory was that “if you could bump up the level of immunity … that should translate into greater protection against shingles,” Wright said. “That basically proved to be the case.”

Adverse effects associated with the vaccine were generally mild, and included headache, and redness, tenderness, swelling and rash at the injection site.

The vaccine is not intended for people who have already had shingles. “Historically, all of the studies have suggested that you only have shingles once,” Wright said. “People who have had shingles (are) considered immune.”

Patients in the study who received the vaccine are being followed to determine how well their immunity holds up against the virus, and whether they may have to be re-vaccinated, he added.

The Shingles Prevention Study was conducted at 22 centers, including 16 Veterans Affairs medical centers, in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID) and Merck, which provided the vaccine and placebo.

Wright said the Vanderbilt portion of the study was funded by the NIAID.