TUESDAY, Oct. 25 (HealthDay News) -- The various health risks associated with being overweight or obese are well known, but a new study now suggests that this extra weight may also make your annual flu shot less effective.
What's more, obese and overweight people may be at higher risk for more severe illness if they do catch the flu, according to the findings published online Oct. 25 in the International Journal of Obesity.
Flu vaccines work by causing protective antibodies to develop in the body. In the study, obese, overweight and healthy weight individuals all developed antibodies to flu viruses within the first month after vaccination, but the antibody levels in the blood waned more rapidly among obese and overweight individuals.
Specifically, there was a fourfold decrease in antibody levels 11 months after vaccination in half of the obese patients, compared to one month post-vaccination. By contrast, less than 25 percent of healthy weight participants showed this degree of decrease in their antibody levels after 11 months, the researchers found.
In addition, a type of white blood cell called CD8+ T-cells, which play a key role in priming the body's immune system, doesn't work properly in heavier people. When vaccination doesn't stave off the flu, people must rely, in part, on these white blood cells to limit the spread and severity of the infection.
"Over time, overweight and obese people are not maintaining their antibody levels to the extent that healthy weight people are," said study author Heather A. Paich, a graduate student at the University of North Carolina at Chapel Hill. "They also appear to have difficulty fighting the flu infection when it does occur."
Whether or not obese or overweight individuals are more susceptible to the flu remains to be seen, she said.
"It has been well-documented that obesity is linked to lowered i
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