The flu shots are reformulated each year based on the mutations. I have had a flu shot every year for years, and I've not had the flu. Of course this is not necessarily a cause-effect situation, but for the great majority of folks this is a simple, cheap thing which can prevent a huge, potentially harmful PITA. My whole family gets them, wife and 2 kids, and none of us have had side effects from the vaccine, and none have gotten the flu.

Rgds,
Chris W.