Immunizations - general overview

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Immunizations

Immunization (vaccination) is a way to trigger your immune system and prevent serious, life-threatening diseases.

See also: Babies and shots

Vaccinations; Immunizations - safety; How immunizations work

HOW IMMUNIZATIONS WORK

Immunizations teach your body how to defend itself when germs such as viruses or bacteria invade it.

• They expose you to a very small, very safe amount of a virus or bacteria that has been weakened or killed.
• Your immune system then learns to recognize and attack the infection if you are exposed to it later in life.
• As a result, you will either not become ill or have a milder infection. This is a natural way to deal with infectious diseases.

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Four different types of vaccines are currently available:

• Live virus vaccines use the weakened (or attenuated) form of the virus. The measles, mumps, and rubella (MMR) vaccine and the varicella (chickenpox) vaccine are examples of this type.
• Killed (inactivated) vaccines are made from a protein or other small pieces taken from a virus or bacteria. Influenza shots are an example of this type of vaccine.
• Toxoid vaccines contain a toxin or chemical made by the bacteria or virus. They make you immune to the harmful effects of the infection, instead of to the infection itself. Examples are the diphtheria and tetanus vaccines.
• Biosynthetic vaccines contain human-made substances are very similar to pieces of the virus or bacteria. The Hib (Haemophilus influenzae type B) conjugate vaccine is one example.

WHY WE NEED IMMUNIZATIONS

Newborns, babies, and toddlers are constantly being exposed to germs from their parents, other adults, brothers and sisters, people in stores, and other children in child care. With travel easier than ever, you and your baby can be exposed to diseases from other countries without you knowing.

For a few weeks after they are born, babies will have some protection, which was passed from their mother through the placenta before birth. After a short period of time, this natural protection goes away.