Childhood Vaccines: How They Work and Why They Matter

What vaccines are

Vaccines — shots, liquids, pills or nasal sprays — teach the immune system to recognize and fight harmful germs (viruses or bacteria).

• Types: some contain germs killed or weakened so they can't make your child sick; some contain only part of a germ; others give cells instructions to make a germ protein.
• How they work: all trigger an immune response. The immune system then remembers the germ and attacks it if it ever returns — immunity.

Why vaccinate

• Babies can fight most germs, but not some serious diseases that once killed or harmed many infants, children and adults. Vaccines give immunity without getting sick — and for a few vaccines, better protection than the disease itself.
• Protecting others: when enough people are vaccinated, a disease can't spread easily — "community immunity." It protects people who can't get some vaccines: those with weakened immune systems, those allergic to an ingredient, and newborns too young for some vaccines.

Are vaccines safe?

Yes. Vaccines go through extensive safety testing before approval in the United States. Many studies have found no link between vaccines and autism spectrum disorder.

Can vaccines overload the immune system?

No. A healthy child's immune system fights off thousands of germs every day. Even several vaccines in one day are a tiny exposure by comparison.

When to vaccinate

Children get vaccines at well-child visits, following the vaccine schedule, which lists which vaccines are recommended, how many doses, and at what ages. In the U.S., CDC publishes it. Following it protects your child at the right time, building immunity before exposure to these serious diseases.

Sources

Based on "Childhood Vaccines," MedlinePlus, U.S. National Library of Medicine; a work of the United States government in the public domain.