A federal panel recommended Wednesday that older people already vaccinated for shingles get a new, better shot.
The advisory group said the just-approved vaccine made by GlaxoSmithKline works better at preventing shingles and may last longer than the one that's been sold in the U.S. since 2006.
Shingles, a painful condition that causes blisters, occurs when the chickenpox virus resurfaces decades later, often when people are in their 60s or older. About 1 in 3 U.S. residents will get it during their lifetime, according to the Centers for Disease Control and Prevention.
At a meeting in Atlanta, the Advisory Committee on Immunization Practices said doctors should first opt for Glaxo's two-dose Shingrix, which uses a new ingredient to boost its effectiveness. It was approved in the U.S. last week, and the committee recommended it for adults 50 and older.
Shingrix has been shown to be 90 percent effective and last at least four years in company-sponsored studies.
"It performs in very superior fashion and will prevent more disease than the other vaccine available," said panel member Dr. Kelly Moore, director of the Tennessee health department's immunization program.
The vote recommending a preference for Glaxo's vaccine over Merck's single-dose Zostavax was unusually close, 8-7. Panel members noted that the two vaccines have not been tested head-to-head yet, and some wanted to wait for more long-term safety information about the new additive used by Glaxo.
But other panel members worried that without citing a preference, many doctors and pharmacies may decide to stock Merck's less expensive vaccine, which costs $232 compared to $280 for the Glaxo vaccination.
Merck's single-dose Zostavax vaccine is recommended for people 60 and older. It reduces the risk by about half, though health officials say its effectiveness drops sharply after about five years.
The panel didn't suggest a time frame when it recommended a Glaxo vaccine for anyone previously vaccinated. Health officials say as many as 20 million Americans would be eligible for a second round.
The shingles vaccine hasn't been very popular; only about 30 percent of those over 60 got it.
The panel's recommendations are almost always adopted by the CDC. But in a statement, Merck officials said they hope the agency will consider some of the issues raised at the meeting and not give a preferential recommendation to Shingrix.
Explore further: US vaccine panel to discuss waning effectiveness, new shots