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 immunity, and I always urge my obese patients at any age to get a flu shot," said Dr. Neil Schachter, a professor of pulmonary medicine at Mount Sinai School of Medicine in New York City.
The fact that their response to the flu shot is impaired has
significant clinical implications, he said. "They may be candidates
for the double flu shot approach that we give to elderly patients
-- one shot in early fall and another in January," he said. "This
may offer better protection for obese patients to avoid the flu or
at least reduce severity of the infection and reduce risk of
Dr. Louis Aronne, founder and director of the Comprehensive
Weight Control Program at New York-Presbyterian Hospital/Weill
Cornell Medical Center in New York City, said that overweight and
obese people may represent another group of people who are at high
risk for flu and flu-related complications. He said more study is
needed to see if these people would benefit from two shots, instead
The bigger picture here is that there needs to be a medical
specialty dedicated to caring for people who are obese, said Dr.
Scott Kahan, an obesity expert at Johns Hopkins University in
"Dosages of certain medications often have to be changed based on weight and, in this case, the flu vaccine dosage or administration may need to be changed," he said. "It may also be that we need enhanced prevention or other adjunctive strategies in addition to the vaccine for flu protection among people who are overweight or obese," Kahan added. These issues are apparent in the treatment or prevention of other disease and conditions as well.
To find where you can get a flu shot, visit the
U.S. Department of
Health & Human Services.