With flu season looming comes the first study showing flu shots dont work as well on the obese – a finding that suggests obesity, like old age, is a major risk factor for severe influenza-related sickness and death.

U.S. researchers have found that the antibody levels produced in response to flu shots fall faster and further in obese people than those of a healthy weight, and that obese people produce defective killer cells, which would usually help fight off flu and other infections.

Obesity lessens flu shot effects