How do flu shots work and why are they recommended annually?

A flu shot helps your body get ready to fight off the flu by giving it a little head start.

Imagine you're playing a game of tag with friends at the park. If you know who's going to chase you, you can run faster and hide better. That’s like what a flu shot does, it tells your body which flu bugs are coming so it can get ready for them.

When you get a flu shot, a tiny bit of weaker flu bugs go into your arm. These aren’t strong enough to make you sick, but they’re just enough to wake up your body’s defenders, called white blood cells. Your body then learns how to fight the real flu bugs when they come around later.

Flu bugs are like tricky kids, they change their clothes and games every year. Sometimes they wear a red shirt, sometimes blue. Your body might remember one version of them, but not all. That’s why you need to get the shot every year, it helps your body learn about the new flu bugs so it can beat them better.

It's like learning a new song each year so you can sing it when it comes up again!