(Updates with GSK comment on patient numbers, launch details)
LONDON, Oct 25 (Reuters) - The committee responsible for U.S. vaccination schedules has given a preferential recommendation to GlaxoSmithKline's newly approved shingles vaccine Shingrix over Merck & Co's established product Zostavax.
The endorsement, by a 8-7 vote, promises to boost Shingrix sales and confirm its potential as a product with multibillion-dollar sales potential.
The backing from the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) follows evidence from clinical trials that Shingrix is significantly more effective than Zostavax, the only currently available shingles prevention vaccine.
ACIP members also recommended that Shingrix should be given routinely to Americans aged over 50 years, compared with 60 years for Zostavax, and they supported revaccination of people who previously received Zostavax.
The new recommendations mean up to 62 million more adults in the United States should be immunised, approximately 42 million aged 50-59 years old and 20 million who have previously been vaccinated against shingles, according to GSK.
Analysts currently forecast Shingrix's annual sales will reach 1.03 billion pounds ($1.37 billion) in 2023, a figure that could rise in light of the positive U.S. recommendations.
However, the British drugmaker, which also reported quarterly results on Wednesday, cautioned it would take time to build up prescription coverage.
GSK's vaccine is given in two doses, while Zostavax needs only a single dose.
Older adults are most at risk of shingles, a painful, often debilitating blistering rash that results from reactivation of the varicella-zoster virus that causes chickenpox and remains latent in those who have had that disease.
Shingrix contains a component from Agenus, which is entitled to royalties on future sales.
$1 = 0.7540 pounds Reporting by Ben Hirschler; Editing by Mark Potter