MELISSA BLOCK, HOST:
This year's flu vaccine looks like it's not doing much to protect older people. New numbers in the Centers for Disease Control and Prevention indicate that the vaccine has only been effective about a quarter of the time for people 65 and older. NPR's Rob Stein joins me to explain what that means. And Rob, tell us more about these numbers coming from the CDC.
ROB STEIN, BYLINE: Right. The latest numbers show that overall the vaccine appears to be about 56 percent effective for everybody, for the entire population, which is about average for a flu vaccine. So that's doing pretty well. But for the elderly it's a very different picture. Overall, for the elderly, it's only, as you said, about 27 percent effective. And the most surprising thing, and the kind of disturbing thing, is that it's only about 9 percent effective for the main strain that's out there that's circulating and causing the most illness.
So for most elderly people, they're really getting very little, if any, protection from this year's vaccine.
BLOCK: And what explains why that is? Does the CDC understand why the vaccine has been so ineffective for the elderly population?
STEIN: Well, the elderly never respond to flu vaccines as well as younger people. And the reason for that is, like a lot of parts of our body, their immune systems just aren't as vigorous as they used to be, so when they're presented with the vaccine, they just don't mount as strong an immune response. And in this case, scientists really don't know why this year's response is even weaker than usual.
One possibility is that they've been exposed to the virus in this year's vaccine many times, so their immune systems have just sort of gotten used to it and so they just don't react to it as strongly as one might hope. But that's just speculation. There's a lot of research that will be needed to really understand what's going on this year.
BLOCK: Well, for elderly people out there who haven't gotten the flu shot this year and are still thinking about getting it, what would you tell them? Should they bother?
STEIN: Yeah, the officials are still recommending that elderly people do go out and get vaccinated and that's because the elderly are among those who really are at the highest risk for life-threatening complications from the flu, so it's really important that they do everything possible to protect themselves. And, you know, at least some protection is better than no protection and also, the parts of the vaccine that protect against other viruses that are circulating seems to be working pretty well.
And there's always the possibility of that those viruses could become more common as this year progresses.
BLOCK: Rob, are there lessons here about how well flu vaccines work and what could be done to make them work better?
STEIN: It really does illustrate that we really have a lot more work to do to make flu vaccines work better. And there already is a relatively new vaccine that's on the market that provides higher doses of vaccine for the elderly and that does seem to produce a more vigorous immune system response. Whether that translates into more protection, we still don't know. But it might and researchers are looking at that.
And down the road, there's a lot of research going on to try to improve the vaccine's effectiveness, including adding what they call aggivants(ph) to the vaccines to boost the immune system response.
BLOCK: And last thing here, Rob, besides getting vaccinated this year, what else should the elderly know about the flu?
STEIN: Well, the reason why the CDC is putting out these numbers and trying to draw attention to them is so that elderly people know that even if they did get the vaccine, they may not be protected. And so if they show any symptoms for the flu, they really should go see their doctor right away and get treated.
BLOCK: Okay. NPR health correspondent Rob Stein. Rob, thanks.
STEIN: Oh, sure. Thanks for having me. Transcript provided by NPR, Copyright NPR.