Obese at greater risk for flu after vaccination

New findings suggest that the overweight and obese may be at a greater risk for catching the flu even if they are vaccinated.

A new study, published online in the International Journal of Obesity, demonstrated that flu antibody levels developed after vaccination wane more rapidly in overweight and obese individuals, in comparison to those of what is considered a healthy weight, according to USA Today.

Influenza vaccines work by spurring the development of antibodies in the human body. Within the first month of the study, all of the subjects developed antibodies to the flu virus. By 11 months after inoculation, however, obese subjects showed a four-fold decrease in their antibody levels. Only 25 percent of healthy weight patients showed a similar decrease after 11 months.

In addition, a type of infection-fighting white blood cell, the CD8+ T cell, which plays a critical role in preparing the immune system, was shown not to work properly in heavier people. If vaccination does not succeed in holding back the flu, these white blood cells play a critical role in limiting the infection’s spread and severity.

“Over time, overweight and obese people are not maintaining their antibody levels to the extent that healthy weight people are," study author Heather Paich, a graduate student at the University of North Carolina at Chapel Hill, said, USA Today reports. "They also appear to have difficulty fighting the flu infection when it does occur."

Paich said that it remains to be seen whether or not the obese and overweight are more susceptible to the flu.

"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," Dr. Neil Schachter, a professor at Mount Sinai School of Medicine in New York City, said, USA Today reports.