Merck's Zostavax is safe and effective for treatment of herpes zoster in adults ages 60 years and older, FDA's Vaccines & Related Biological Products Advisory Committee unanimously agreed at its Dec. 15 meeting.

"It's important to acknowledge that they have shown what is quite an impressive reduction in the instance of herpes zoster in those 60 and over," committee member Monica Farley (Emory University) said.

[Editor's note: To ¹ watch a webcast or order a video/DVD of this meeting, visit FDAAdvisoryCommittee.com.]

The committee said the data presented were not sufficient to support Merck's proposed use for the vaccine in adults ages 50-59. Merck is seeking indications for Zostavax (live varicella zoster vaccine) in the "immunization of adults = 50 years for prevention of herpes zoster, post-herpetic neuralgia and reduction of acute chronic zoster associated pain" (² Also see "Merck Zostavax Shingles Vaccine Decreases In Efficacy Over Three-Year Period, FDA Review Finds" - Pink Sheet, 14 December, 2005.).

"Obviously, we cannot say there are any data to support licensing between ages 50 to 59. It's unfortunate in the sense that my guess is it will work once the company actually does the studies," committee member David Markowitz (University of Michigan) remarked. "Until we have the studies we can't really comment." Only about 150 of the 38,000 patients in Merck's Zostavax study were in the 50-59 year age range.

One of the committee's concerns regarding immunization of people in their 50's is that the efficacy of the vaccine may wane and later expose subjects to herpes zoster and post-herpetic neuralgia at a point in life when the risk of severe pain is greater.

"Is it possible that the effect of this vaccine is not to prevent herpes zoster but to just prolong its occurrence...in terms of the time when you would get herpes zoster?" committee member Daniel Scharfstein (Johns Hopkins University) questioned.

Merck maintained that the efficacy of the vaccine does not diminish over time, but rather stabilizes after an initial decrease in efficacy shortly following immunization.

Merck plans to evaluate a booster dose in future studies.

-Mary Bruce

Merck Zostavax Shingles Vaccine Safe and Effective For Adults Over 60, Committee Says

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