Right now, if you're a relatively healthy person, a flu shot might reduce your personal risk of coming down with the flu by 40 percent to 60 percent. But getting a flu shot also does something else: It helps protect the people around you who are most vulnerable to serious flu illness, particularly the very old and the very young. A vaccine that is 60 percent effective on a 30-year-old, for instance, may be only 30 percent effective on someone over 65. Babies are notably hospitalized for influenza at alarming rates.