WASHINGTON, Dec 14 (Reuters) - Merck & Co. Inc's (MRK.N: Quote, Profile, Research) data showed its experimental vaccine to prevent shingles helps curb related pain but did not significantly affect rates of death or hospitalization, U.S. regulatory staff said in documents released on Wednesday. But company data also showed the vaccine, called Zostavax, did not significantly reduce rates of death or hospitalization and became less effective after three years, U.S. Food and Drug Administration staff said before an advisory panel meeting on Thursday to discuss the product.
Zostavax showed no "particular pattern" of serious side effects, the staff also said.
The panel of outside health experts will weigh whether to recommend approval by the FDA, which usually follows its advisers' advice.
Merck is also seeking approval for another vaccine to help prevent rotavirus, the most common cause of diarrhea in children. A panel meeting to discuss that product is being held on Wednesday.
