How do vaccines stimulate the immune system to prevent disease?

Vaccines teach your body how to fight germs before they make you sick.

Imagine your immune system is like a superhero team that protects you from villains, the germs and bacteria that cause illness. But when they first appear, the superheroes don’t know what they look like, so they take time to figure out how to beat them. That’s why you might feel tired or achy when you get sick, your body is working hard to fight off the germ.

Vaccines are like training videos that show your superhero team a picture of the villain before the real battle happens. These pictures are made from weakened or inactive germs, or parts of them, so they can’t hurt you. When you get a vaccine, your body sees these little bits and goes to work, it makes special soldiers called antibodies that remember how to fight that germ.

Next time the real germ comes along, your immune system already knows what it looks like and can stop it quickly, before you even feel sick! It’s like practicing for a race, you get faster at running when you train.