Narrator: This is Science Today. Hopefully by now, those at highest risk of influenza have already rolled up their sleeves and received their flu shot. Mary Lynch, a professor of nursing at the University of California, San Francisco, says it typically takes at least two weeks before the body can generate an appropriate antibody response to the bug.
Lynch: So that if you're exposed to someone with the flu, if you got the flu shot yesterday and that person has the flu today, you're still likely to get it. On the flip side, if you had the vaccine three weeks ago and someone coughs at you and they have the flu vaccine, you're more likely to be protected.
Narrator: But the flu vaccine does not provide 100 percent protection because the older we get, the less efficient our bodies respond to vaccines.
Lynch: But what we have seen in individuals with chronic illnesses and older individuals is that receiving the flu shot may prevent some of the more serious complications.
Narrator: For Science Today, I'm Larissa Branin.