The finding on the experimental shingles vaccine comes from a huge, carefully conducted clinical trial in 38,546 people aged 60 and older. Michael N. Oxman, MD, of the VA San Diego Healthcare System and the University of California, San Diego, led the study.
"There is real hope that in the near future we will make a big reduction in the adverse impact of shingles on older people everywhere," Oxman tells WebMD.
The findings appear in the June 2 issue of The New England Journal of Medicine.
A Vaccine for Older Adults
Shingles -- doctors call it herpes zoster -- is caused by the same virus that causes chickenpox. A person who gets chickenpox gets over the illness, but the chickenpox virus stays in the body. It hides at the root of nerve cells along the spine, where the body's immune system keeps it in check.
As a person ages, this immune protection gets weaker. The virus can reawaken and travel along the nerves to the skin, where it causes the painful, blistering lesions typical of shingles. This stimulates the immune system a second time -- and for most people with a healthy immune system, this time the virus remains under control for the rest of a person's life.
However, nearly one in eight cases of shingles results in a condition known as postherpetic neuralgia. This results in extreme pain in the nerves themselves. This pain can last for months or even years. Normal pain medication does not help.
"Postherpetic neuralgia is very painful," Oxman says. "It can lead to a breeze blowing on your forehead or the touch of a shirt on your skin becoming excruciating."
According to the National Institute of Neurological Disorders and Stroke, doctors now recommend starting antiviral drugs within 72 hours of the first sign of the shingles rash. Early treatment is believed to reduce the risk of postherpetic neuralgia and may speed up the healing process.
Vaccine Cuts Pain, Severity
The chickenpox vaccine can prevent illness in children. It's a live virus vaccine made with an extremely weak strain of herpes zoster virus. Oxman's team used the same vaccine in adults. But because most adults already are immune to the virus, they had to use a much larger dose of the vaccine to get an effect.
Half the people in the study got the vaccine, and half didn't. The results:
- The vaccine cut shingles cases by 51%.
- The vaccine reduced shingles severity by 61%.
- The vaccine reduced cases of postherpetic neuralgia by 66.5%.
That last number is the most important one, says herpes virus expert Sam Speck, PhD, professor of microbiology and immunology at the Emory Vaccine Center and director of the center for emerging infectious diseases at Emory University in Atlanta.
"For individuals over 60, it may be worth getting vaccinated if this vaccine becomes available," Speck tells WebMD. "If the vaccine's protection was simply limited to preventing the bout of shingles, it would be less of a good idea. But it is the prevention of postherpetic neuralgia that really drives interest in this vaccine."
Merck, which makes the vaccine, already has asked the FDA to approve the vaccine. But it's not easy to make. Right now, Oxman says, his team is waiting for Merck to give them more vaccine so they can give it, as promised, to the nearly 20,000 study participants who received placebo during the study. Merck is a WebMD sponsor.
Questions Remain
Questions remain about the shingles vaccine, notes Stanford University researcher Ann Arvin, MD. Arvin's editorial accompanies the Oxman study in the NEJM.
Arvin points out that:
- It's still not clear how long the vaccine protects against shingles and postherpetic neuralgia.
- It's still not clear whether repeat doses of the vaccine will improve protection.
- If a second or third dose is needed, the best vaccination schedule is not known.
- It's still not clear whether the vaccine will work in very old people.