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Immunization: Quick Facts

By The Manuals's Editorial Staff

Vaccines are needed to protect people, especially children, against infectious diseases.

  • Typically, children are given a number of vaccines according to a standard schedule.
  • Also, all adults regularly need some vaccinations, such as the influenza vaccine every year and the tetanus vaccine every 10 years.
  • Other vaccines are usually given mainly to specific groups of people, such as those who are traveling to certain parts of the world (for more information, see Vaccines for International Travel).

Giving a vaccine stimulates the body's immune system to defend against a specific disease. Vaccination produces a state of immunity to the disease and is thus sometimes called immunization.

Vaccines are usually given by injection into a muscle (intramuscularly) or under the skin (subcutaneously).

For a full discussion, see Overview of Immunization, and for children, see Childhood Vaccination.

Why Are Vaccines Important?

Vaccines have eliminated smallpox and have nearly eliminated other infections, such as polio and measles, which were once common childhood scourges in the United States. Despite this success, it is important for children to continue to be vaccinated. Many of the diseases prevented by vaccination are still present in the United States and are common in other parts of the world. These diseases can spread rapidly among unvaccinated children, who, because of the ease of modern travel, can be exposed even if they live in areas where a disease is not common.

Did You Know...

  • Children in the United States still die from diseases that can be prevented by vaccines.

  • Unvaccinated children are 23 times more likely to contract pertussis (whooping cough).

  • Unvaccinated children are 8.6 times more likely to contract varicella ( chickenpox).

  • Unvaccinated children are 6.5 times more likely to contract pneumococcal disease (including meningitis, pneumonia, and middle ear infections).

Are Vaccines Effective and Safe ?

No vaccine is 100% effective and 100% safe. A few vaccinated children do not become immune, and a few develop side effects. Most often, the side effects (such as pain at the injection site, a rash, or a mild fever) are minor. Very rarely, there are more serious problems. Vaccines are continuously undergoing improvements to ensure safety and effectiveness.

Vaccines and Autism

The public press has reported concerns that the measles-mumps-rubella (MMR) vaccine may cause autism. It does not. These concerns were based on a brief medical report in 1998 about 12 children with developmental disorders such as autism. Since then, doctors have done many studies to look for a connection between the vaccine and autism. No such connection was found in any of the studies. Doctors found that the children who had been vaccinated were no more likely to develop autism than those who were not vaccinated.

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* This is the Consumer Version. *