Does the flu vaccine work as well in elderly people?

Ask the doctors

Q. My mother is in her late 80s. She received the flu vaccine this year, but I heard that it won't be as effective because of her age. Is this true?

A. The flu vaccine can be less effective in elderly adults. That's because the flu vaccine works by priming the body's own immune system to mount a response to the virus if it's encountered. Older adults may have weaker immune systems, and therefore a weaker immune response to the vaccine.