Scientists Solve Mystery Of Flu Strains' Origins

Solving a 60-year-old mystery, researchers have concluded that new flu strains emerge in eastern and southeastern Asia, move to Europe and North America six to nine months later, then travel to South America, where they disappear forever.

The new findings should help researchers pick the correct flu strains for each year's vaccine, a process that must be carried out a year ahead of time and that is now analogous to making a long-term weather forecast supported by only limited data.

The group charged with making the decisions about vaccines has been right about 80% of the time, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, and the new findings should lead to an even higher success rate.

"If we have competing candidates, this will help to pick which virus should go in a vaccine," added Dr. Arnold Monto, an epidemiologist and flu specialist at the University of Michigan.