Study: Flu shots less effective on obese people

Here's yet another good reason to lose weight.

New research from the University of North Carolina at Chapel Hill shows that annual flu shots may be less effective for obese people.

The study, reported online in the International Journal of Obesity, reports for the first time that influenza vaccine antibody levels decline significantly in obese people compared to people who maintain a healthy weight.

"These results suggest that overweight and obese people would be more likely than healthy weight people to experience flu illness following exposure to the flu virus," said Melinda Beck, Ph.D., professor and associate chair of nutrition at the UNC Gillings School of Global Public Health and senior author of the study.

Researchers studied people at a clinic who had been vaccinated in late 2009 with the common flu vaccine for that fall and winter season. Although obese, overweight and healthy weight individuals all developed antibodies to flu viruses within the first month after vaccination, the antibody levels in the blood declined more rapidly in obese and overweight individuals over time, according to the study.

And, when study participants' blood samples were tested in the lab and exposed to a flu virus 12 months after the vaccination, about 75 percent of people with a healthy weight still retained an infection-fighting protein. But, only about 25 percent of obese patients' cells responded by producing the protein, researchers said in a press release.

"The findings also suggest overweight and obese people are more likely to become sicker and have more complications," added Heather Paich, a doctoral student in Beck's lab.