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Immunization: The Basics

Unless we can "stop the leak" (eliminate the disease), it is important to keep immunizing. Even if there are only a few cases of disease today, if we take away the protection given by vaccination, more and more people will be infected and will spread disease to others. Soon we will undo the progress we have made over the years.

On this page, you'll review the basic definitions of terms. And, then go to information that explains why we immunize, what would happen if we stopped vaccinating, see what diseases are prevented by vaccinating, and get answers to common questions.


Definition of Terms

Let's start by defining basic terms:

Immunization: The process by which a person or animal becomes protected against a disease. This term is often used interchangeably with vaccination or inoculation.

Vaccination: Injection of a killed or weakened infectious organism in order to prevent the disease.

Vaccine: A product that produces immunity therefore protecting the body from the disease. Vaccines are administered through needle injections, by mouth and by aerosol.


Links to Basic Immunization Information

  • Why immunize?
    Why immunize our children? Sometimes we are confused by the messages in the media. First we are assured that, thanks to vaccines, some diseases are almost gone from the U.S. But we are also warned to immunize our children, ourselves as adults, and the elderly.
  • Brief overview of adult and childhood vaccine-preventable diseases and vaccines
    In our mobile society, over a million people each day people travel to and from other countries, where many vaccine-preventable diseases remain relatively common. Without vaccines, epidemics of many preventable diseases could return, resulting in increased - and unnecessary - illness, disability, and death among children and adults.
  • 10 things a parent should know about immunizations
    Lists the top 10 things such as how many doses your child needs, diseases vaccines prevent, side effects, etc.
  • How immunity works: types of immunity
    See and learn how those that are vaccinated help protect those that are not or cannot be vaccinated.
  • Common questions
  • What would happen if we stopped vaccinations?
    In the US, vaccination programs have eliminated or significantly reduced many vaccine-preventable diseases. However, these diseases still exist and can once again become common—and deadly—if vaccination coverage does not continue at high levels.
  • Life-cycle of immunizations
    See how if enough people stop getting immunized, disease numbers will start to rise again, and there will be outbreaks. The chart tracks the evolution of a single disease, from a time when there was no vaccine to when the disease is eradicated.
  • Vaccine availability timeline
    Dates when vaccines first became available.

See also: Vaccines: The Basics


Related Information and Materials

  • The Parents' Guide to Childhood Immunizations
    68-page booklet introducing parents to all childhood diseases and the vaccines that can protect children from them
  • The Vaccines for Children Program
    The Vaccines for Children (VFC) Program offers vaccines at no cost for eligible children through VFC-enrolled doctors. Find out if your child qualifies. Vaccinating on time means healthier children, families and communities.


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