New York Times
To a patient, few things look bigger than that needle a doctor is about to plunge who-knows-where to administer a vaccine.
But some doctors are arguing that in many cases, those syringes ought to be even bigger.
Writing in a recent issue of The British Medical Journal, the doctors said that for some people, especially overweight ones, the needles were simply too small to be effective.
They cited a recent study of 220 adults that found that the standard needle (which they said was five-eighths of an inch long) could not penetrate the upper arms of 17 percent of the men and 50 percent of the women because of variations in the thickness of fat.
For men weighing 130 to 260 pounds, and for women weighing 132 to 198 pounds, it may be better to use a one-inch needle, the researchers said. And for women above 198 pounds, they said, a one-and-a-half inch needle may be in order.
"It is essential that vaccines reach the muscle to ensure that the body's immune response is triggered and to reduce the likelihood of an adverse reaction," the journal said.