Hundreds of thousands of Americans get shingles (herpes zoster) each year. Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox in children. After a child recovers from chickenpox, the varicella-zoster virus remains in nerve cells, where it may become reactivated later in life and result in an outbreak of shingles.

Decreased immunity to the varicella-zoster virus is associated with an increased risk and severity of shingles. It is not surprising, then, that shingles usually occurs in older people and people with compromised immune systems (e.g., cancer patients, people with AIDS , and recipients of organ transplants).

Shingles begins with a burning, itching, or tingling sensation on the skin, usually in the back, chest, abdomen, or face area. Two to three days later, an itchy rash may develop and erupt into blisters that resemble a localized, crowded case of chickenpox. In 1-2 weeks, the sores crust over, before healing within another two weeks.

Shingles blisters are associated with pain that can be intense. A particularly devastating complication of shingles, postherpetic neuralgia, is characterized by severe pain that persists or develops after the blisters have healed. In some cases, postherpetic neuralgia can persist for years, seriously diminishing a person’s quality of life.

Medications can reduce the severity and duration of a shingles outbreak, but they cannot prevent postherpetic neuralgia. A new study in the June 2, 2005 issue of the New England Journal of Medicine found that a varicella-zoster virus vaccine significantly reduced the incidence of shingles and postherpetic neuralgia in people over age 60.

About the Study

This study included 36,716 participants ages 60 and older who had a history of chickenpox or had lived in the continental United States for 30 years or longer. People with compromised immune systems were excluded from the study.

The participants received either a varicella-zoster vaccine or a placebo injection, and were followed for three years. They participated in a monthly survey designed to identify possible cases of shingles. Researchers evaluated all possible cases, and confirmed a shingles diagnosis with a blood test.

The researchers kept track of serious adverse events in all participants for six weeks after the vaccination. In addition, 6,616 participants were monitored for less serious side effects such as fever or symptoms related to the injection site.

Each person with confirmed shingles completed the Zoster Brief Pain Inventory, a questionnaire that measures shingles-associated pain and discomfort. Researchers used responses to this questionnaire and reports of postherpetic neuralgia to calculate each participant’s relative “burden of illness.”

The Findings

During the study, 984 cases of confirmed shingles were documented.

The participants in the vaccine group had significantly lower burden of illness scores than those in the placebo group. Specifically, the vaccine reduced the incidence of shingles by 51.3% and postherpetic neuralgia by 66.5% compared with the placebo group. Furthermore, the vaccine group experienced significantly reduced duration of pain and severity of illness.

The vaccine was generally well tolerated. However, allergic reactions, pain or tenderness, swelling, itching, and other problems at the injection site were more common in the vaccine group (48.3% versus 16.6%, respectively). Also, 1.9% of participants in the vaccine group and 1.3% of participants in the placebo group had serious adverse events (e.g., exacerbation of asthma , life-threatening allergic reaction); this difference was significant.

During the six weeks after vaccination, there were seven confirmed cases of shingles in the vaccine group and 24 in the placebo group, suggesting that the vaccine did not cause or induce shingles.

While the study was well-designed and carefully executed, it is important to note that it was partially funded by Merck, the pharmaceutical company that manufactures a varicella-zoster vaccine.

How Does This Affect You?

These findings indicate that the vaccine used in this study markedly reduces the incidence of shingles and postherpetic neuralgia, as well as the overall burden of illness due to shingles, in people ages 60 and older. This is significant, since shingles is common and sometimes serious in this population.

The study vaccine was at least 14 times more potent than the Food and Drug Administration (FDA)-approved version of the vaccine used to prevent chickenpox in children. And other studies have indicated that less potent vaccines are not beneficial in preventing shingles.

The author of an accompanying editorial points out that the study vaccine is extremely cost-effective when the cost of the vaccine is weighed against the benefits seen in this study. And although adverse events were more common in the vaccine group, most were minor. Therefore, if the FDA approves the more potent version of the varicella-zoster vaccine in the near future, older adults may soon be able to significantly reduce their risk of developing shingles and postherpetic neuralgia by getting vaccinated.