Data on 2,697 children and adults showed this year's flu vaccine has been effective in 56% of people who were vaccinated. The vaccine provided better protection against influenza B, and better protection against influenza A among younger people compared with older people. Just 9% of those 65 and older who were vaccinated were protected against influenza A. The findings in the Morbidity and Mortality Weekly Report highlight the need for a better and longer-lasting vaccine against flu, CDC officials said.