Vaccines tell your own immune system how to prevent certain kinds of disease. A vaccine
uses a tiny amount of substance that lets your body build up antibodies and other
defenses to a virus or bacteria. This helps to prevent or lessen the severity of many
types of diseases caused by infection.
A vaccine is most often done with an injection by a small needle into your arm. Some
vaccines work in 1 shot. Others need to be done in 2 or more shots over a period of
time. This lets your immune system build up the right amount of defenses.
Combination vaccines can help prevent more diseases with fewer shots. These vaccines
have more than one type of prevention in a single dose.