The Food and Drug Administration (FDA) licensed Zostavax, on May 25, 2006, a new vaccine to reduce the risk of shingles (herpes zoster) for use in people 60 years of age and older.
Shingles is a disease caused by the varicella-zoster virus, the same virus that causes chickenpox. After an attack of chickenpox, the virus lies dormant in certain nerve tissue. As people age, it is possible for the virus to reappear in the form of shingles, which is estimated to affect 2 in every 10 people in their lifetime. Shingles is characterized by clusters of blisters, which develop on one side of the body and can cause severe pain that may last for weeks, months or years after the virus reappears.
"This vaccine gives health care providers an important tool that can help prevent an illness that affects many older Americans and often results in significant chronic pain," said Jesse L. Goodman, MD, MPH, Director of FDA's Center for Biologics Evaluation and Research.
Zostavax, a live virus vaccine, was shown to boost immunity against varicella-zoster virus. This is thought to be the mechanism by which the vaccine protects against zoster and its complications. The vaccine is given as a single injection under the skin, preferably in the upper arm.
Zostavax was studied in approximately 38,000 individuals throughout the United States who were 60 years of age and older. Of these 38,000 people, half received Zostavax and half received a placebo. All study participants were then followed for an average of three years to see if they developed shingles and, if they did, how long the pain lasted.
At the conclusion of the study, researchers found that, overall, in those ages 60 and above the vaccine reduced the occurrence of shingles by about 50%. For individuals ages 60-69 it reduced occurrence by 64%.
In addition to preventing approximately half of the cases, the duration of pain following the onset of shingles was slightly reduced in people who developed the disease–despite being vaccinated with Zostavax.
The most common side effects in people who received Zostavax were redness, pain and tenderness, swelling at the site of injection, itching and headache. The percent of significant adverse events observed in the study were not different between persons who received the vaccine versus placebo.
As part of the development program, a smaller study was conducted to look more closely at safety. In this smaller study, serious adverse events for all age groups were noted more frequently in those who received Zostavax (1.9%) than those who received placebo (1.3%). Although FDA has concluded that the available data do not establish that these events are related to the vaccine, the manufacturer will perform a Phase 4 (postmarket) study to provide additional safety information.
Zostavax is manufactured by Merck & Co., Inc., of Whitehouse Station, New Jersey.