In a new study, the researchers report that using a standard 1-inch needle to immunize obese adolescents against hepatitis B virus produced a much weaker effect than using a longer needle. "As obesity rises in the US, we need to be aware that the standard of care may have to change to protect obese youth," study co-author Dr. Amy Middleman of Baylor College of Medicine in Houston told Reuters Health…

The results are no surprise, said Dr. Gregory Poland, who studies vaccines at the Mayo Clinic in Rochester, Minnesota. For years, doctors have known that vaccines tend not to work as well in heavy people. Whether the obese have weaker immune systems, or fat keeps shorter needles from reaching muscles, where the vaccines can affect immune cells, was unclear.

Reuters by Fredrik Joelving, 2/8/2010

Tags: immune systems, Infectious Diseases, obese, vaccines