Vaccine

health · immune system · disease prevention · science

Training Your Immune System. A vaccine contains a weakened or killed germ (or just a tiny piece of it) that looks like a real disease-causing microorganism. When you get vaccinated, your immune system learns to recognize this fake invader and practices destroying it.

Your Body's Memory. After a vaccine, your immune system remembers what that germ looks like. If the real, dangerous germ ever tries to infect you, your body recognizes it instantly and defeats it before you get sick.

Safe Practice. Vaccines use weakened or killed versions of germs, so they can't actually make you sick with the full disease. This lets your body build protection without facing the real danger.

Diseases Nearly Eliminated. Vaccines have helped humanity wipe out terrible diseases like smallpox and have made others like polio extremely rare. Millions of lives are saved every year because of vaccines.