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Monday, August 08, 2005

A Dubious Bird Flu Vaccine

This article at the Agonist disease outbreak forum illustrates why doctors aren't feeling very ebullient about the vaccine trials for bird flu:
Enthusiasm over the news that U.S. researchers have proven a vaccine is effective against the H5N1 avian flu strain was tempered Monday with word that it took massive doses - roughly 12 times the normal amount - to produce a protective response in humans.

With global vaccine production capacity already falling far short of what would be needed in a flu pandemic, experts suggested it is critical to ramp up research into ways to produce the same response with smaller doses of antigen, the substance in a vaccine that activates the immune system.

"I think these results suggest the world is even less prepared than more prepared," said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

"And unfortunately many policy makers might take this announcement as being 'We've hit the gold mine' - when in fact I would suggest we are having a hard time even finding water."
I gather they feel the results of the trials were a big disappointment. Even worse, there's a strong suspicion that the vaccine is unlikely to work against a strain that achieves efficient human to human transmission:
Dr. Guan Yi, a Hong Kong University microbiologist, said that the flu virus that has just appeared this summer among migratory birds roosting on an island in Qinghai Lake in western China had quite a few genetic differences from previous viruses that had circulated in Southeast Asia.

The previous viruses appear to have been used in the successful vaccine tests this spring and summer in the United States.

"It keeps changing, it keeps evolving," he said. "We don't know how much the vaccine matches."
So the vaccine is producing an exceptionally weak immune response in humans and it is also probably not matched well to what we're really trying to avoid. Not encouraging.

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