Test results show bird flu vaccine needs more work


The first major test of an experimental vaccine being stockpiled against the possibility of a bird flu pandemic found that it triggers protective immune responses in about half of the healthy adults who were given a high dose.

The results, to be published today in the New England Journal of Medicine, gave health officials reason to hope as well as cause for concern. Though the vaccine appears to be safe, it does not protect everyone, and the large dose required means it would be difficult to make the vaccine quickly and in quantity in an outbreak.

"We have a vaccine we know can spur an immune response, albeit at very high doses. We're going in the right direction. The sobering news is we have a long way to go," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded the study.

Researchers now will begin investigating ways to reduce the required dosage, such as by adding an immune booster.

"We actually have a product," said Dr. John Treanor, director of Rochester's Vaccine and Treatment Evaluation Unit and the overall leader of the project. "We're not there yet, but we're making progress."

Others were not as optimistic.

"The study shows that it is going to be very difficult to have a vaccine ready to vaccinate the U.S. population should bird flu transmit from human to human," said vaccine expert Robert Lamb of Northwestern University.

Researchers working on a vaccine against the bird flu virus face steep hurdles. Scientists have called the H5N1 strain "a moving target" that is evolving quickly as it spreads; the vaccine being stockpiled was based on a strain isolated in Southeast Asia in 2004.

The disease also has been around for nine years without infecting many humans; the virus would have to change drastically for it to be passed easily from person to person.

The U.S. government has funded studies of more than 30 candidate vaccines, Fauci said, and early results from some of these trials should be available in the next year. Others are being developed by the World Health Organization Influenza Network.

The government began stockpiling the experimental vaccine known as 1203, manufactured by Pennsylvania-based Sanofi Pasteur, last summer and has 8 million doses available. However, the new research suggests that amount would cover just 4 million people, given the large amount required. The ultimate goal is to be able to treat 20 million people, Fauci said.

"It's obviously a small step, but at least we have something that could buy us some time," Fauci said of the stockpiling. "It would probably go to first-responders, especially hospital personnel, in case of an emerging pandemic."

The virus, which has caused outbreaks among birds in more than 30 countries, also has infected some mammals. As of Friday, 186 people had been infected with avian flu viruses after coming into contact with infected birds. More than half have died.

Peter Gorner writes for the Los Angeles Times.

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