Vaccine Basics

Vaccines play an important role in keeping us healthy. They protect us from serious and sometimes deadly diseases — like haemophilus influenzae type b (Hib) and measles.

It’s normal to have questions about vaccines. works with scientists and doctors to answer your questions and provide the information you need to get vaccinated.

In this section of the site, you’ll find the answers to common questions like:

Once you have the information you need, make sure that you and your family are up-to-date on your vaccinations — they’re your best shot against serious, preventable illness. Find more answers to common questions about vaccines.

A few helpful terms

As you learn about vaccines and how they protect you, it may be helpful to understand the difference between vaccines, vaccinations, and immunizations.


A vaccine is made from very small amounts of weak or dead germs that can cause diseases — for example, viruses, bacteria, or toxins. It prepares your body to fight the disease faster and more effectively so you won’t get sick.

Example: Children younger than age 13 need 2 doses of the chickenpox vaccine.


Vaccination is the act of getting a vaccine, usually as a shot.

Example: Schedule your tetanus vaccination today.


Immunization is the process of becoming immune to (protected against) a disease.

Example: Because of continued and widespread immunization in the United States, it’s rare for Americans to get polio.

Immunization can also mean the process of getting vaccinated. For example, your “immunization schedule,” is the timing of your shots