First Step Toward Lifelong Flu Vaccine?

There's a possible breakthrough in the fight against the flu.

It might mean getting a flu shot once, and having it last the rest of your life, warding off the virus, reports CBS News correspondent Michelle Gielan.

Scientists believe they've discovered the Achilles Heel shared by all flu strains, she says.

"Until this study was published, we had no idea there was a common element of all influenza viruses," Dr. Wayne Marasco of the Dana Farber Cancer Institute told CBS News.

The flu virus, Gielan explains, is cloaked by lollipop-shaped proteins. The circular part at the top of the "pops" constantly mutates, but researchers have found that the pops' "sticks" (stem), which contains the machinery that enables the virus to attack a cell, never changes.

Until now, all our vaccines have been directed at the circular part, which is why there's a seasonal vaccine administered every year, Gielan continues. But with this breakthrough, scientists have developed an anti-body drug that attacks the stem.

It is, they say, the first step in possibly developing a vaccine that could give people lifelong immunity against even the bird flu. Such a drug could be crucial in preventing a global flu epidemic.

Every year, 36,000 people in the U.S. die from flu.

But, says Marasco, "This is the first step in a well-defined pathway to develop these into drugs that can be used to treat and prevent influenza in people."

If testing goes well, some scientists say a version of the vaccine could be in clinical trials within two years, Gielan points out.