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Merits of Novel Bird Flu Vaccine Studied

Posted on: Thursday, 12 October 2006, 18:00 CDT

By LAURAN NEERGAARD

WASHINGTON - A unique study suggests there may be a way to kick-start people's protection against bird flu just in case it triggers a worldwide outbreak years from now.

If a flu pandemic began, it would take several months to tailor a vaccine to the precise strain causing illness and then to make enough vaccine for every American. Worse, people almost certainly will require two doses to protect against a flu strain their bodies have never before encountered.

Scientists have long wondered if giving shots in advance might help - a vaccine that wouldn't fully protect but would introduce people's immune systems to a brand new type of flu. Then, once a pandemic began, they'd need only one booster shot of vaccine tailored to the exact strain, significantly cutting the time it would take to protect a population.

Friday, University of Rochester scientists will report the first evidence that this so-called "prime-and-boost" method might work.

They tracked down 37 people who had tested an experimental bird flu vaccine back in 1998.

That was a year after the H5N1 virus flu is known to have made its first jump into people in Hong Kong, and the experimental shots matched that Hong Kong strain. The deadly Asian bird flu has evolved since then as it made repeated jumps into people in different countries.

Eight years after the volunteers got those first bird flu shots, the Rochester scientists gave them each a single booster dose - this time made from a very different H5N1 strain that emerged in Vietnam in 2004.

The booster method worked better than simply vaccinating people with the Vietnam strain for the first time, the scientists will report Friday at a meeting of the Infectious Diseases Society of America.

More than twice as many of the booster shot recipients had a protective immune response compared with those who got a single first-ever vaccine. And the booster recipients even responded a little better than those who got two first-ever doses.

Source: Associated Press/AP Online

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