This doesn't mean you should avoid vaccination. The flu shot will still prevent infection in many people. And if you do get infected, the antibodies you form in response to the shot can still blunt the effects of the illness.
If you want to increase the odds that a flu shot will work for you, exercise and physical fitness can be key. Scientists have found that in elderly, sedentary people, a 10-month program of brisk walking significantly improved responses to flu vaccination.
Prescott, a physician and medical researcher, is president of the Oklahoma Medical Research Foundation. Cohen is a marathoner and OMRF's senior vice president and general counsel.