The flu is a devious adversary, constantly shifting its shape to outwit our defenses. But the mind of Robert Webster is equally agile. Last year, Webster, 71, working at St. Jude Children's Research Hospital in Memphis, confronted H5N1, a virulent Asian strain. To beat it, Webster's lab developed a vaccine in record time, using a radical new method: inserting two key bits of the virus's genetic code into a much milder strain. The result of this "reverse genetics" technique is a harmless bug that teaches the body's immune system to attack the killer flu. The next hurdle is convincing the World Health Organization—and a wary public—that a genetically manipulated vaccine poses no new dangers. "These are bad, bad viruses" that demand the swiftest possible response, says Webster. "We are saying you can use these techniques for good."

*The name of this award was originally the Impact Award. In 2008, the awards were renamed as the Inspire Awards.