Plenty of people – about 1 in 3, according to some studies — feel bad for a day or two after they get a flu shot. The most common symptoms include headaches, muscle aches, fatigue and fever, all of ...

A late-emerging influenza A mutation known as subclade K weakened protection, but doctors say vaccination still reduces ...

Even without a perfect match, public health experts say the flu vaccine offers important protection against serious ...

A variant of influenza A, H3N2, is spreading across the U.S., with low vaccination rates contributing to infection rates.