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The parade of flushed faces through Dr. Jacqueline Spencer's medical practice in Long Island City, N.Y., usually starts in November, when brisk weather and runny noses help viruses make the rounds. These days, Spencer is busier than usual: she's moonlighting as a "sentinel"--one of 80 or so doctors who sends a regular tally of fevers and raspy coughs to New York City's health department. Health officials aren't interested in Spencer's opinions or diagnoses. They want raw data that could signal the onset of a new epidemic. By analyzing pharmaceutical orders, emergency-room admissions and 60,000 other seemingly disparate facts each day, experts can sometimes spot an outbreak before individual doctors have noticed an uptick in cases. Although the system has worked well in recent flu outbreaks, its most important test may lie ahead. The deadly bird-flu virus is now rampant among the poultry farms of Asia, and many experts think it's only a matter of time before the bug acquires the ability to pass from one human to another.
A human variant of the bird-flu virus, known as H5N1, would be a formidable foe. Only 44 people have caught H5N1 (from direct contact with birds), but 32 of them have died--a mortality rate of 73 percent. And because flu bugs spread so rapidly, a human version of H5N1 could quickly infect billions of people worldwide, claiming millions of lives. An effective vaccine is our best hope of heading off a pandemic, and scientists are now racing to create one.
They've already taken the first step. Scientists at St. Jude Children's Research Hospital in Memphis, Tenn., 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 that the immune system uses to identify an invader--and attached them to a benign virus that could be administered to people. The resulting vaccine has worked on animals, and the U.S. government has awarded contracts to Chiron and Aventis to produce enough vaccine to start human clinical trials in the new year.
The trials will test whether the vaccine is safe and whether it prompts the immune system to produce antibodies for H5N1 (a simple blood test will tell). Scientists will study the vaccine in healthy adults first, and then test it in children and the elderly. If all goes well, clinical trials could be finished by March. Then manufacturers would have to produce it in massive quantities. Because H5N1 is radically different from any previous flu bug, scientists think the average person would need two doses to acquire immunity. Producing 600 million doses would require a doubling of the nation's flu-vaccine capacity.
That's a tall order. The current vaccine candidate will be produced in chicken eggs--a laborious process that has changed little since the 1940s. Even if the vaccine proved safe and effective, vaccine makers would need six to eight months after clinical trials to produce the first batch. The government's preparedness plan, released in draft form in August, aims to create enough "surge capacity" to scale up production at the first sign of a pandemic. There is currently no plan to stockpile H5N1 vaccine in anticipation of one. If the worst happens, some health experts say that the best defense may be a public-awareness campaign reminding people to wash their hands, wear a mask in public or perhaps even avoid social gatherings. But with luck and a lot of effort, we will have other weapons on hand.