AGS: Shingles Vaccine Booster Is in the Cards after Four Years

SEATTLE, May 7 -- Immunogenicity from the live attenuated herpes zoster vaccine (Zostavax) -- unlike herpes -- is not forever, post-marketing data suggest.

Although the vaccine's protection lasts for at least four years, the data suggest that a booster shot may be needed for longer-term protection, said Kenneth Schmader, M.D., of Duke University at an industry-sponsored symposium held in conjunction with the American Geriatrics Society meeting here.

He noted that researchers have anticipated the need for a booster because the herpes vaccine is a super-potent formulation of the varicella vaccine, for which recent studies have confirmed a pattern of fading protection.

Dr. Schmader was a co-investigator of the pivotal Shingles Prevention Study that led to FDA approval of the herpes zoster vaccine and is a member of the CDC's Advisory Council on Immunization Practice (ACIP) working group on the vaccine.

The vaccine was approved for prevention of herpes zoster and postherpetic neuralgia in people ages 60 or older.

Rafael Harpaz, M.D., M.P.H., acting chief of the herpes virus team at the CDC, said clinicians should assess requests for the vaccine on a case-by-case basis, but added that it was unlikely that the vaccine would offer a benefit beyond the natural protection offered by infection with wild type herpes zoster.

Last fall the vaccine advisory council approved a provisional recommendation that endorsed use of the vaccine for persons age 60 or older "whether or not they report a prior episode of herpes zoster."

In an interview, Dr. Harpaz said the final ACIP recommendation was on his desk and was scheduled for release this fall. He said he did not anticipate any major changes from the provisional recommendation.

Asked about number needed to treat and cost-effectiveness of the vaccine, Dr. Schmader said the American College of Physicians' journal club calculated that one case of herpes zoster would be prevented for every 55 people vaccinated and 350 immunizations were needed to prevent one case of postherpetic neuralgia.

Dr. Harpaz said the CDC has attempted a number of analyses, but "the cost effectiveness has varied from ,000 to ,000 per case averted, so it is just too hard to nail down a figure."

Paying for the vaccine has been a problem for Medicare patients, Dr. Schmader acknowledged at the Merck-funded event, because of the coverage mechanics of Medicare Part D.

The risk of herpes zoster-and postherpetic neuralgia-increases exponentially after age 60, noted Michael Oxman, M.D., chief of infectious diseases at VA Medical Center, San Diego and principal investigator of the Shingles Prevention Study.

Data from that study suggest that universal vaccination of all Americans age 60 or older would eliminate just over half of the estimated 556,000 herpes zoster cases per year, Dr. Oxman added, and more than two-thirds of the cases of postherpetic neuralgia.

The use of the vaccine in people younger than 50 remains unanswered, said Dr. Oxman.

"It's an off label use, but if I have a faculty member's wife who is 53 and has had an episode of herpes zoster and wants the vaccine-and is willing to pay for it-I am probably going to give it to her," Dr. Oxman said. "But I'm going to explain that she will probably need a booster shot."