Shingles Vaccine Shown Effective in Large VA Trial

Stronger version of the chickenpox vaccine cuts incidence and severity of painful nerve and skin infection in older adults

Tampa FL (June 2, 2005) -- In one of the largest adult vaccine trials ever, researchers have shown that an experimental vaccine against shingles prevented about half (51 percent) the cases of the painful nerve and skin infection. The experimental vaccine -- a more potent form of the vaccine routinely used to immunize children against chickenpox-- also reduced severity and complications in vaccinated adults who got shingles. The findings appear in the June 2 issue of the New England Journal of Medicine, coauthored by John Toney, MD.

The Shingles Prevention Study was a Department of Veterans Affairs (VA) Cooperative Study in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID) and Merck & Co., Inc. More than 38,500 men and women, age 60 or older, participated at 22 sites across the United States, including 16 VA medical centers and six clinical sites coordinated through NIAID. The James A. Haley Veterans' Hospital, an affiliate of the University of South Florida Health Sciences Center and the only site in Florida, enrolled 1,200 participants.

This landmark study has important implications for the prevention of shingles and a complication called postherpetic neuralgia, pain originating in damaged nerves that plagues some older people for months, even years, after an attack of shingles, said Dr. Toney, associate professor of medicine in the Division of Infectious Diseases at USF and director of health care epidemiology at James A. Haley Veterans' Hospital.

The vaccine worked and was safe. It reduced the incidence of shingles by half. Even the vaccinated people who developed shingles got milder cases and experienced less neuralgic pain than those receiving placebo.

The vaccine used in the study is called the zoster vaccine. Half of the study participants received a placebo. The other half were inoculated with the same attenuated (weakened) virus as that administered to children to prevent chickenpox, but the shingles vaccine used significantly more of the virus to be effective in older adults.

During an average of more than three years follow-up, 642 cases of shingles occurred in the placebo group, compared to only 315 in the vaccinated group. The total burden of pain and discomfort caused by shingles was reduced by 61 percent in vaccine recipients compared with placebo recipients. Moreover, vaccinated subjects were only a third as likely as placebo recipients to develop postherpetic neuralgia (PHN), a form of chronic nerve pain that is the most common serious complication of shingles. The vaccine was well tolerated by older adults, with the most common side effect being redness, soreness and swelling at the site of injection.

Anyone who ever had chickenpox is at risk for shingles. The same virus that causes chickenpox, called varicella-zoster virus, also triggers herpes zoster, or shingles. When a child recovers from chickenpox, the virus doesn't disappear. Instead, it hides out in clusters of nerve cells, called sensory ganglia, near the spinal cord. For most people the virus remains dormant the rest of their lives. However, weakened immunity brought on by advancing age, stress or disease may reactivate the virus causing it to multiply, damage the sensory ganglia and then migrate to the skin, where the blistering rash of shingles appears.

Although the rash heals in two to four weeks, about 1 in 8 older people with shingles experience nerve pain lasting three months or longer. For some, the pain can be aggravated by something as slight as clothing touching the skin or a cool breeze.

Postherpetic neuralgia can make life extremely miserable and is notoriously difficult to treat, said Dr. Toney. Burning, itching, gnawing, stabbing, throbbing and aching are how people describe the pain. One patient said everytime the wind blows it feels like someone is rubbing sandpaper over part of my body.

Antiviral medications can speed the healing of shingles and reduce the severity of nerve damage caused by the disease, but only if used within 72 hours of the first sign of a shingles rash. Antiviral medications do not help relieve postherpetic neuralgia once it has begun.

Merck has submitted the vaccine to the Food and Drug Administration for approval. The researchers emphasized that the vaccine was tested only as a preventive therapy and is not intended for those who already have shingles or postherpetic neuralgia.

James A. Haley Veterans' Hospital/USF is one of 12 sites from the original Shingles Prevention Study included in an extension arm of the trial seeking to collect more information on people vaccinated against shingles.

USF

The University of South Florida Health Sciences Center is comprised of the colleges of Medicine, Nursing and Public Health and united by one mission to advance collaborative learning and discovery leading to improved health in our community. USF has major affiliations with the area's teaching and research hospitals, providing an important diversity of educational experiences. In partnership with its affiliated hospitals, the Health Sciences Center's research funding jumped 21 percent last year to $145.4 million more than half of which came from federal sources.