Scientists Study Flu Vaccine in Elderly
RENEE MONTAGNE, Host:
Scientists are debating the effectiveness of the flu vaccine in the elderly. Some are now saying that the vaccine may be much less effective in people over 65 than has been claimed. One thing scientists on both sides of the issue do agree on - older people should get vaccinated.
NPR's Joanne Silberner has more.
JOANNE SILBERNER: At least one flu fact is indisputable. About 90 percent of Americans who die from the flu are 65 or older. So protecting older people can save a lot of lives. But how many lives does the flu vaccine actually save?
David Shay is a medical officer in the influenza division of the Centers for Disease Control and Prevention. He points to a study done in 1994 of people over age 60.
DAVID SHAY: Fifty percent for a disease that has the risk of serious complications in older people isn't as good as we would like, but it's a heck of a lot better than not getting vaccinated.
SILBERNER: And other flu expert credit the flu vaccine for cutting in half the incidents of wintertime deaths among elderly people. But Lorna Simonson(ph) says the percent may not be that large. She used to be with the National Institute of Allergy and Infectious Diseases and is now with George Washington University. She and several others analyzed as many flu studies as they could find.
LORNA SIMONSON: We had to go back and review all the evidence that was available from all kinds of different studies.
SILBERNER: They looked at that 1994 study that showed a 50 percent reduction in flu incidents and noticed that the vaccine was much less effective in older people. They looked at studies comparing people who decided to get vaccinated to those who didn't, and figured that fewer of the vaccinated people died because they were healthier in the first place, healthy enough to go out and get a vaccine.
And they threw out other studies like the ones that showed decreases in wintertime deaths because of methodological problems.
SIMONSON: It's like putting together the - all the pieces of the puzzle.
SILBERNER: Simonson and her colleagues published their analysis in the journal Lancet Infectious Diseases. In the end, they couldn't prove that the flu shot helps the elderly survived the flu season.
SIMONSON: We were surprised to see that. We didn't see that reduction as we had expected it to be.
SILBERNER: She says her analysis doesn't rule out an effect, but it certainly does not show a big one.
Still, the CDC's David Shay said the 1994 study that took a group of people and gave half of them a placebo and half of them have a vaccine is solid enough evidence that the flu vaccine is very effective.
SHAY: That's our one piece of gold standard evidence in people in this age group.
SILBERNER: And he dismisses one of Simonson's concerns. She noted that some studies showed the overall death rate in the elderly did not go down as vaccine use went up. Shay says other factors could be making up the difference.
SHAY: So it's very difficult to make an assessment of how vaccine worked when you're not connecting the vaccine's status back to the individual who died.
SILBERNER: Simonson says there probably is a reduction in death. It's just that no one has definitively proved how large it is. Simonson and Shay agree on several things.
SIMONSON: It's the best available prevention that we have for influenza, and influenza is a serious disease that causes lots of deaths in seniors. So if there are some benefits of the vaccine, it's far better than no vaccine at all; that's clear.
SILBERNER: Not just for the elderly, but for everyone, including children, who can transmit the disease to their parents and grandparents. The two sides also agreed that while people are getting vaccinated, scientists need to work on a way to make the current vaccine work better in the elderly, or else find a new one.
Joanne Silberner, NPR News.