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(Removes incorrect name Pandemrix, paragraph 2)
By Toni Clarke
Nov 22 (Reuters) - The U.S. Food and Drug Administrationsaid on Friday it has approved a vaccine made by GlaxoSmithKlinePlc for use in the event of an H5N1 bird flu epidemic.
The vaccine will be added to the national stockpile and willnot be available for commercial use, the FDA said. The vaccinedoes not have a trade name in the United States.
It is the first H5N1 vaccine approved in the United Statesto contain an adjuvant, or booster, that turbo-charges thebody's immune response to the vaccine.
"This vaccine could be used in the event that the H5N1 avianinfluenza virus develops the capability to spread efficientlyfrom human to human, resulting in the rapid spread of diseaseacross the globe," Dr. Karen Midthun, director of the FDA'sbiologics division, said in a statement.
The FDA approved the vaccine for use in people over the ageof 18 who are at increased risk of exposure to the virus. Itwould be distributed by public health officials if needed.
The approval comes amid some uncertainty over the safety ofmodern adjuvants such as the one used in GSK's bird flu vaccine.
However, there are no truly effective traditional vaccinesagainst bird flu. Glaxo's super-charged product is the first toshow it can confer protection in the event of a pandemic.European regulators have approved it under the brand namePumarix.
Data shows that children in England who received a similaradjuvanted vaccine, Pandemrix, during the 2009-10 H1N1 swine fluepidemic had a 14-fold heightened risk of developing narcolepsy,a chronic and potentially debilitating sleep disorder that cancause hallucinations, daytime sleepiness and cataplexy, a formof muscle weakness precipitated by strong emotion.
According to GSK, some 30 million doses of Pandemrix wereadministered across Europe and 800 people, mostly children,developed narcolepsy. While GSK has acknowledged an associationbetween the vaccine and the narcolepsy cases, it has said thereis insufficient evidence to prove the adjuvant was to blame.
Adjuvants have been used in vaccines for diseases such asdiphtheria and tetanus for decades. Now, a new, more powerfulgeneration of adjuvants, including one known as AS03 that iscontained in the bird flu vaccine, is being developed whosesafety is relatively untested.
Previously, the United States has taken a more cautiousapproach toward adjuvants than some other countries. The FDA didnot, for example, approve Pandemrix. U.S. experts felt thattraditional, non-adjuvanted H1N1 vaccines made by SanofiSA and others offered enough protection against thevirus.
But an advisory panel voted unanimously that the FDA shouldapprove the vaccine against bird flu, which kills nearly 60percent of those who become infected. By comparison, the H1N1virus kills fewer than 1 percent of those infected.
The H5N1 bird flu virus was first isolated in a human inHong Kong in 1997 and began to spread throughout Southeast Asiain 2003. A 2011 report by the World Health Organization showedonly 566 people had been infected with bird flu worldwide,compared with millions infected with the 2009 H1N1 swine fluvirus. But the death rate for bird flu is far higher. (Reporting by Toni Clarke; Editing by Leslie Adler)
