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, Pandemrix, will be added to the nationalstockpile and will not be available for commercial use, the FDAsaid.
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 effective traditional vaccines againstbird flu. Glaxo's super-charged product is the first to show itcan confer protection in the event of a pandemic. Europeanregulators have approved it under the brand name Pumarix.
Data shows that children in England who received a similaradjuvanted vaccine during the 2009-10 H1N1 swine flu epidemichad a 14-fold heightened risk of developing narcolepsy, achronic 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 for H1NI swine flu. U.S.experts felt that traditional, non-adjuvanted H1N1 vaccines madeby Sanofi SA and others offered enough protectionagainst the virus.
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.
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