Bird-flu virus neutralized in vaccine tests

WASHINGTON — An experimental vaccine appears to be effective against a strain of flu virus that experts fear could spark a devastating pandemic, offering the first evidence that any inoculation could provide a powerful weapon against the deadly microbe, a federal health official said Saturday.

Two doses of the vaccine produced an immune system response potent enough to neutralize the virus in tests on 113 volunteers who were injected as part of a federally sponsored study being conducted at three U.S. universities.

"This is very good news," said Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "This is the first vaccine that anybody has that has been tested to show that you can actually produce a robust immune response."

Public health authorities are alarmed by a strain of flu virus known as H5N1, which has been spreading primarily in birds across Asia and in Russia. It also has infected nearly 100 humans in the past 18 months, killing about half of them. If the virus starts to spread efficiently among humans, experts fear it could trigger a global pandemic that could kill millions.

In response, millions of birds throughout Asia have been slaughtered to try to stem the spread of the virus; governments and the World Health Organization have been stockpiling antiviral drugs, and scientists have been scrambling to produce an effective vaccine.

Much more testing will be needed to determine exactly how the vaccine could be used, and other hurdles remain, including being able to produce and distribute large quantities of vaccine in event of a pandemic, Fauci said. But he said the results represent a crucial milestone.

"The data are pretty solid," Fauci said. "They're preliminary but solid. Having a vaccine in case we had a pandemic flu is a very important part of a comprehensive response to a pandemic."

Other experts agreed that the tests marked a key step in the world's attempt to prepare for a possible pandemic.

"These are very important studies," said Michael Osterholm of the University of Minnesota. "This is confirmation of what we hoped would be the case. We all had anticipated that two doses were going to work. If it didn't, we would be in trouble."

But Osterholm said the world still would be woefully unprepared if a pandemic occurred. The capability to produce and distribute a large amount of vaccine quickly, for example, is far from adequate.