Climate change could exacerbate flu epidemic, study finds

NEW YORK — While experts say climate change could produce a wide range of side effects, a new one could be earlier and more severe flu seasons, according to a new study.

Researchers at Arizona State University and Northeastern Illinois University — led by ASU Mathematical, Computational and Modeling Sciences Center research professor Sherry Towers — studied influenza and climate patterns in the United States from the 1997-1998 season to the present using data from the Centers for Disease Control and Prevention. They found that strong flu seasons usually followed warm winters, a pattern that held true for the A and B strains of influenza.

"It appears that fewer people contract influenza during warm winters, and this causes a major portion of the population to remain vulnerable into the next season, causing an early and strong emergence," Towers said. "And when a flu season begins exceptionally early, much of the population has not had a chance to get vaccinated, potentially making that flu season even worse."

The researchers noted that the current season started early and fiercely, despite a relatively light 2011-2012 season that coincided with the fourth warmest winter on record; flu transmission decreases in warm and humid conditions, according to previous studies. But if global warming continues, warm winters will become more common, and the effects of the flu will be stronger.

"The expedited manufacture and distribution of vaccines and aggressive vaccination programs could significantly diminish the severity of future influenza epidemics," ASU mathematical epidemiologist Gerardo Chowell-Puente said.

The study, published online Monday in PLoS Currents: Influenza, received partial support from the Multinational Influenza Seasonal Mortality Study, overseen by the National Institutes of Health's Fogarty International Center.

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