This year's flu vaccine appears to be doing a unusually poor job of protecting the elderly, federal health officials reported Thursday.
Overall, this year's flu vaccine appears to be only about 27 percent effective for people ages 65 and older, the Centers for Disease Control and Prevention reports in this week's Morbidity and Mortality Weekly Report.
But, perhaps more important and more concerning, it looks like it's only about 9 percent effective in protecting people 65 and older against the H3N2 flu strain that's causing the most illness this season, the CDC says.
That compares with an overall effectiveness for all ages is about 56 percent, which is around the average for a flu vaccine.
Flu vaccines never work as well among older people because their immune systems tend to be weaker. But this year's protection seems to be unusually low. Officials aren't sure why.
Despite the feeble protection, the CDC is still urging the elderly to get vaccinated. They're among those most vulnerable to life-threatening complications from the flu, and some protection is better than none.
"Influenza vaccines remain the best preventive tool available," according to the MMWR.
But older people who get vaccinated should be aware that they still might get the flu and see a doctor right away if they think they do, the CDC says.
"Early antiviral treatment can reduce influenza-associated illness severity and complications," the MMWR says. "This season, antiviral treatment of elderly adults is especially important."
The low protection of this year's vaccine underscores the need for "continuing efforts to develop more effective vaccines and vaccination strategies," according to the MMWR.