FDA panel backs shingles vaccine for 60 and older.(Clinical Rounds)

BETHESDA, MD. -- The available data clearly support the safety and effectiveness of a herpes zoster vaccine for people aged 60 and older, the age group that made up most of the participants in clinical trials, a 14-member federal advisory panel unanimously agreed at a meeting in December.

However, the information on safety and efficacy of the vaccine in people aged 50-59 was inadequate because of a lack of data for this age group and uncertainty over the duration of immunity after vaccination, according to the Food and Drug Administration's Vaccine and Related Biological Products Advisory Committee.

Merck & Co., the manufacturer of the live attenuated varicella-zoster virus (VZV) vaccine, has proposed that it be approved for preventing herpes zoster (shingles), preventing postherpetic neuralgia (PHN), and reducing acute and chronic zoster-associated pain in patients aged 50 years and older, although the pivotal trial enrolled patients aged 60 years and older.

That trial, the Shingles Prevention Study, compared the vaccine with placebo in over 35,000 subjects ages 60 years and older. The incidence of herpes zoster was reduced by 51%, the incidence of PHN by 66.5%, and the burden of illness (a composite measure of herpes zoster pain incidence, severity, and duration) decreased by 61% over a median 3 years' follow-up; all were highly significant differences.

As a rationale for including people in their 50s, Dr. Jeffrey Silber, senior director of clinical research at Merck, maintained that routine use of the vaccine in this age group could prevent 110,000-130,000 cases of herpes zoster and 8,000-15,000 cases of PHN a year in the United States. This vaccine could also prevent work productivity loss because most people in this age group are still working.

And because immune responses in the pivotal trial were comparable across age groups, and similar age-related findings were seen in other smaller studies of the vaccine, efficacy for younger people is expected to be as good as that seen in older people, Dr. Silber said.

Postmarketing studies should look for waning immunity and evaluate the need for a booster and the effect of a booster over time, panelists recommended. Overall, the panel agreed that in those patients studied, the data provided good evidence of the durability of the response after vaccination that persists for 3-4 years, the longest period of time recipients were followed.