Doctors know it as zoster, but up to a million Americans are stricken each year by the infection they call shingles. By either name, it's an unsightly, often painful process that can be prevented by a vaccine that was approved in 2006.
The culprit is varicella-zoster virus (VZV), the same virus that causes chickenpox (varicella in children). The vast majority of children recover completely, but that's not the end of the story. Instead of being killed and eliminated from the body, VZV goes into hibernation, hiding out in the part of the nervous system known as the sensory nerve ganglia. In most people, the virus remains dormant and harmless for life, but in up to 15%, VZV becomes active and causes shingles.
Most patients with shingles are older than 60, and some have weakened immune systems. The virus spreads along the sensory nerve to form a line of blisters on one side of the body. Most patients recover fully, but a few develop serious complications, and up to a third develop long-lasting pain (post-herpetic neuralgia). Antiviral medicines, which are often prescribed with steroids, can reduce the risk of pain.
Chickenpox has become rare in American children, thanks to the varicella vaccine that was licensed in 1995. But 90% of American adults had chickenpox as children, and all of them are at risk for shingles.
Enter the new vaccine. It is similar to the pediatric varicella vaccine, but it contains a much larger dose of the weakened VZV virus than the chickenpox vaccine does.
A major 2005 trial in 38,546 adults age 60 and older found the vaccine safe and effective. It reduced the incidence of shingles by more than 51%, and it lowered the risk of persistent pain by more than 66%. The most common side effect was pain at the injection site, which was usually mild.
The new vaccine, Zostavax, is suggested for people age 60 and older but should not be given to those who have immune systems that have been weakened by certain malignancies, therapy with steroids or other immune-suppressing medications, or HIV infection. Zostavax must be kept frozen until it is used, and it is expensive. Doctors don't yet know how long the vaccine's protection will last or if booster shots will be needed.
June 2007 update