For decades, researchers have been doggedly pursuing a universal flu vaccine--one that would protect against the evolving influenza virus for years rather than just a single season--with little success. The bug mutates so quickly that a new vaccine must be specially formulated each year. But a relatively new strategy, targeting a rarely seen portion of the virus, is now showing some success.
While vaccines for other infections can create immunity that lasts for decades, the flu virus has proved a more challenging adversary. Because the human immune system is so adept at recognizing it, the virus has evolved the ability to modify its most recognizable protein--called hemagglutinin--from year to year. So every year, six months prior to flu season, the U.S. Food and Drug Administration devises the country's annual vaccine according to its best guess for which strains will be most virulent. And every year, we need another flu shot.
Palese's experimental vaccine, however, targets a part of the hemagglutinin protein that remains relatively stable over time, enabling its broad immunizing effects.
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