Cover your coughs in the Carolinas and don't double dip in Denver. A Tulane University study published in the American Journal of Health Economics found cities with teams in the Super Bowl see a rise in flu deaths.

Lead author Charles Stoecker of Tulane University School of Public Health and Tropical Medicine along with economists Alan Barreca of Tulane and Nicholas Sanders of Cornell University looked at county-level statistics from 1974-2009. The researchers found having a team in the Super Bowl resulted in an average 18 percent increase in flu deaths among those over 65 years old, a population more vulnerable to serious complications from influenza.

"It's people that are staying at home and hosting small local gatherings, so your Super Bowl party, that are actually passing influenza among themselves," says Stoecker. "Every year, we host these parties that we go to and it changes mixing patterns and you are coughing and sneezing and sharing chips and dip with people that you often don't and so we get the influenza transmitted in novel ways that's then going to eventually wind up in the lungs of a 65-year old."

The effects are greater when the Super Bowl occurs close to the peak of flu season or when the dominant influenza strain is more lethal. Models show this year's flu season could be a mild one, but the virus will still kill thousands of people and sicken many more.

Researchers found no increase in flu deaths in cities hosting the Super Bowl. Stoecker says that's because the game has traditionally been held in warmer locales where the environment is less favorable for transmission.

Stoecker says preventive measures are the most effective in fighting the flu, getting vaccinated and washing hands. And if that's not enough, his suggestion: A giant sign above the dip that says, "Scoop once."

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