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Researchers develop new method for forecasting flu outbreaks

Scientists have developed a computer model for predicting flu outbreaks weeks in advance, raising the tantalizing possibility of "flu forecasts" that might one day help guide such decisions as when to ramp up vaccine production or close schools.

The new flu model, described in a study published this week in the Proceedings of the National Academy of Sciences, incorporates techniques used in weather prediction to forecast flu outbreaks up to seven weeks in advance.

Researchers at Columbia University and the National Center for Atmospheric Research focused their study on the winters between 2003 and 2009 in New York City.

The formula used data from the Google Flu Trends project, which estimates outbreaks based on the number of flu-related search queries in a given region. The model also incorporated findings from a previous study that found wintertime U.S. flu epidemics tended to occur following very dry weather.

Scientists say the model represents a first step in flu forecasting and would need to be adjusted based on such factors as geography — peak flu season varies from region to region — and the strain of influenza.

"Flu forecasting has the potential to significantly improve our ability to prepare for and manage the seasonal flu outbreaks that strike each year," Irene Eckstrand, a program director at the National Institutes of Health, said in a statement.

Local experts say the model could be a tool they would use when planning for flu season.

"To me it seemed a sort of breakthrough," said Dr. John Sinnott, director of the University of South Florida Health's Division of Infectious Disease and International Medicine.

He said a practical use of the model is likely at least a year away, pending additional refinement. But he said an accurate prediction of peak flu season could be critical for vaccine manufacturers, who need a few weeks to ramp up production. It might also help hospitals determine staffing levels during flu season, or encourage vulnerable patients to get vaccinated, he said.

Dr. Douglas Holt, an infectious disease expert who is director of Hillsborough County Health Department, called the study "intriguing."

"It makes a lot of sense," he said. "Do I see it being something we'd utilize? I'm not so sure. If we assume it's accurate, I think it would help us further refine our message and our timing of the message about when to take precautions."

Worldwide, influenza kills an estimated 250,000 to 500,000 people each year. The U.S. annual death toll is about 35,000. Federal health experts advise that nearly everyone over the age of 6 months get a flu shot, but many Americans don't bother. Some think flu isn't that serious while others believe wrongly that you can get flu from the vaccine itself.

The vaccine takes a little time to become effective, another reason it would be helpful to get advance warning that a wave of disease is on the way.

One of the authors of the study, Alicia Karspeck of the National Center for Atmospheric Research in Boulder, Colo., said in an interview that her project represents a potential turning point in the study of influenza: The formula is aimed at predicting future outbreaks, rather than modeling past ones.

The federal Centers for Disease Control tracks flu patterns by relying on lab data and doctor visits — not exactly the perfect tool with which to predict day-to-day surges in cases. The Florida Department of Health also produces weekly flu reports. According to last week's report, Tampa Bay counties are experiencing what the state calls "mild" levels of flu cases.

The new flu model takes into account the latest search data from Google Flu Trends. Earlier this year, researchers at Johns Hopkins Medicine reported that the Flu Trends data strongly correlates with an upswing in emergency room activity, suggesting the project could be a powerful early warning system for frontline health care workers.

The study was funded by the National Institutes of Health and the Department of Homeland Security. NCAR is sponsored by the National Science Foundation.

Sinnott said he doesn't think forecasting for New York City would be dramatically different than for Florida. In both areas, he said, dry weather plays a significant role in flu outbreak because of indoor heating, which can dry up the nasal secretions that help protect against the flu virus.

Besides, he said, "the flu doesn't respect boundaries."

"You could be on a plane today and be in New York," he said.

Jodie Tillman can be reached at jtillman@tampabay.com or (813) 226-3374.

Researchers develop new method for forecasting flu outbreaks 11/27/12 [Last modified: Tuesday, November 27, 2012 11:10pm]

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