Merck's Zostavax approved as shingles-prevention treatment

By Elaine Rigoli

Tampa, Fla., May 26 - The Food and Drug Administration has approved Merck & Co.'s new vaccine Zostavax for prevention of herpes zoster, commonly referred to as "shingles," in individuals 60 years of age and older.

The approval of Zostavax is based on studies of more than 40,000 people, more than 21,000 of whom received the active vaccine.

The efficacy and safety of a single dose of Zostavax was evaluated in the largest of these studies, the landmark Shingles Prevention Study of 38,546 men and women age 60 and over who had no previous history of shingles, Merck said in a news release.

In the study, participants were randomized to groups given either Zostavax or a placebo and followed for the development of shingles for a median duration of 3.1 years. All subjects with clinically diagnosed shingles were offered antiviral treatment, as well as standard-of-care treatment for pain, as necessary.

Zostavax reduced the risk of developing shingles compared with a placebo by 51% (315 cases vs. 642 cases) in the shingles prevention study, the release said.

The efficacy of Zostavax for the prevention of shingles was highest for those 60 to 69 years of age and declined with increasing age.

Overall, the benefit of Zostavax in the prevention of long-term nerve pain from shingles (postherpetic neuralgia) can be primarily attributed to the vaccine's effect on the prevention of shingles, the release said.

Merck said vaccination with Zostavax reduced the incidence of long-term nerve pain from shingles in individuals 70 years of age and older who were vaccinated with Zostavax but went on to develop shingles.

Following completion of the shingles prevention study, a separate analysis was conducted to evaluate the reduction in postherpetic neuralgia in the group of individuals who had been vaccinated with Zostavax but who had developed shingles.

In the analysis, Zostavax reduced the overall incidence of postherpetic neuralgia by 39% compared to the placebo group.

Further, a statistically significant reduction in postherpetic neuralgia was seen in individuals aged 70 to 79 (55%) and a nonstatistically significant reduction in postherpetic neuralgia was seen in those aged 60 to 69 (5%) and 80 and older (26%) in the analysis.

Merck is a global pharmaceutical company based in Whitehouse Station, N.J.

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