Obesity may make flu vaccine less effective, study suggests

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Being obese may increase the risk of coming down with the flu, even after receiving a flu vaccine, new research suggests.

Investigators at the University of North Carolina Family Medicine Center studied 74 people who received a flu shot in the 2009-2010 season, and measured their antibody response a month after receiving the vaccine. They retested the antibody response again after a year.

One-third of the group was normal weight; one-third was overweight; and members of sthe remaining third were obese. After a year, more than half of the obese patients had a fourfold or greater decrease in antibodies, compared to 25% of the patients at normal weight levels.

“These findings suggest a mechanism for the increased risk of severe disease from pH1N1 infection in the obese population,” the authors wrote. “[Obese individuals] … may be at risk for suboptimal vaccine response.”

The study appeared in the International Journal of Obesity on Oct. 25.