Bird-Flu Challenge; An avian-flu outbreak could kill millions. Will we have a vaccine in time to stop it?(Cover Story)

Byline: Michael Hastings and Fred Guterl (With Sarah Schafer in Beijing and Joe Cochrane in Bangkok)

For Zhang Jianxin, a poultry farmer at the forefront of the virus wars, the threat of an influenza pandemic wasn't something that should be left to health officials a world away. Zhang's livelihood depends on the health of his chickens, and last winter 14,000 of them stood in the path of a deadly bird flu. When he had the chance to vaccinate his flock for $550--a small fortune in his village outside of Xinle city, where the average family earns $100 a year--he took it. "I thought the quality would be better if the price was high," says Zhang. But the medicine, it turned out, was a fake. In 10 days, 7,000 birds died. "I sold the ones that survived," he says, "because they were in bad shape."

Health authorities have been struggling to contain the bird-flu virus, known as H5N1, ever since it surfaced in Asia's poultry farms in 1997, with mixed success. The virus is now a fixture, and officials are growing more urgent in their warnings about the possible repercussions. Many experts are convinced that H5N1 will eventually acquire the ability to spread from human to human. The consequences could be devastating. The virus is lethal--it's killed 32 of the 44 people who've contracted it, a mortality rate of 73 percent--and, like any flu virus, it spreads quickly. An H5N1 pandemic, a World Health Organization scientist said last week, could infect billions of people and, in the worst case, result in 100 million deaths.

The prospect of a human H5N1 pandemic has pushed health officials into a state of high alert this winter. They're racing the clock to prepare a vaccine that might block the virus. They're also closely watching Asian poultry farms, trying to keep a stubborn bird bug from turning into a deadly human pathogen, or at least limiting its destructive power.

The best strategy, of course, would be to stop the virus in its tracks before it turns into a bona-fide human pathogen. Health officials appear to be on the losing side of that battle. Right now the virus appears to be thriving in the poultry farms of China, Thailand and Vietnam. Efforts over the past few years to cull infected birds have failed to wipe out the disease. Last year a new strain that proved fatal to chickens and ducks prompted farmers to begin buying vaccines on the black market to keep their chickens alive. Many of these vaccines weren't developed specifically for H5N1, which means they keep the chickens healthy but don't manage to kill the virus. That leaves the infected chickens alive to act as breeding grounds for virus. For this reason, Thailand banned the use of poultry vaccines. China, on the other hand, has been promoting the vaccination of its birds. Nobody knows how many Chinese farmers are using bogus or inappropriate vaccines.

If scientists can't kill H5N1 at the source, the next best thing is to be able to inoculate people against it. They've already taken the first step. In the past few months, scientists at St. Jude Children's Hospital in Memphis, Tennessee, have designed a vaccine against the H5N1 virus. They used a new technique called reverse genetics, which allowed them to assemble the vaccine, Tinkertoy style, from its genetic constituents in only a few months. They isolated H5N1's "surface proteins"--knoblike structures ...