Knowing the source should lead to more effective vaccines, researchers say
WEDNESDAY, April 16 (HealthDay News) -- Each year, new strains of virus that produce seasonal flu epidemics start in East Asia and Southeast Asia and then spread around rest of the world, researchers report.
And by focusing on new flu strains emerging in Asia, scientists may be able to improve their forecast of seasonal flu strains and develop better vaccines, the researchers said.
"For over 60 years, the global migration pattern of influenza has been a mystery," lead researcher Colin Russell, of the University of Cambridge in England, said during a Wednesday teleconference.
Conventional wisdom has held that flu viruses migrate between the northern and southern hemispheres after the flu season. Other theories contend that the viruses surface in the tropics and circulate continuously, or start out in China, Russell said.
"We found solid evidence that influenza H3N2 viruses [the most common viruses] have migrated out of what we call the East and Southeast Asian circulation network, which includes tropical, subtropical and temperate countries," Russell said.
Virus strains begin in East and Southeast Asia and take about nine months to reach Europe and North America. They arrive in South America several months later because of South America's isolation in terms of travel from East and Southeast Asia, Russell explained.
Currently, the decision about which strains to include in the yearly flu vaccine are made almost a year before the flu hits the United States, co-author Derek Smith, also from the University of Cambridge, said during the teleconference. Knowing where flu patterns begin will be invaluable in helping to develop more effective vaccines earlier, he added.
"The ultimate goal is to increase our ability to predict the evolution of influenza virus, and this study is one step along that path," Smi
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