Why is it important that all children get vaccinated?

Unvaccinated children are capable of spreading the disease to other children, even those who have been vaccinated since no vaccine is 100% protective.

Vaccines have minimized or eliminated outbreaks of certain diseases that were once lethal to large numbers of people, including measles and polio in the U.S and smallpox worldwide. But because the bacteria and viruses that cause diseases still exist, the public health gains can only be maintained by ensuring that vaccination rates remain high enough to prevent outbreaks.