Last year, you might have heard how the flu vaccine was less effective than usual. That's because the creation of the vaccine is basically a guessing game - experts pick a few varieties to include in the vaccine, a bunch of that vaccine is produced, and we all hope that the flu varieties which actually show up in the wild match the vaccine. Sometimes the guesses are good, and sometimes they're not.
But none of that means getting a flu shot is a bad idea. Even if the guess isn't very good, the vaccine can still provide some protection. And if the guess is good, having the protection can mean a much lower chance of the misery that comes with having the flu.
So now, I get the shot every year. Some years I get sick, some I don't...but I'm convinced that I'm avoiding at least some instances of being miserably sick. And that's worth a little pin-prick once a year.