Immunize Canada      Immunisation Canada

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What is immunization?

When you get sick, your body generates antibodies to fight the disease and help you get better. These antibodies stay in your body even after the disease has gone, and protect you from getting the same illness again. This is called immunity. You don’t have to get sick to develop immunity; you can be given a vaccine. Immunity through immunization

Immunization (or vaccination) protects people from disease by introducing a vaccine into the body that triggers an antibody response as if you had been exposed to a disease naturally. The vaccine contains the same antigens or parts of antigens that cause the disease, but the antigens in vaccines are either killed or greatly weakened.

Vaccines work because they trick your body so that it thinks it is being attacked by a disease. Immunity through immunization happens without the consequence of being ill and without the risk of potential life-threatening complications from the disease. Memory cells prevent re-infection when they encounter that disease again in the future.

However, not all vaccines provide lifelong immunity. Diseases such as tetanus require booster doses every ten years for adults to maintain immunity.

Why is immunization important?

When children are not immunized, they are at risk of infection from vaccine-preventable diseases and can also infect others. Immunization is the most effective way to protect children from the most common childhood diseases.

When is it time to be immunized?

Children should be immunized according to the recommended immunization schedule in their respective jurisdiction. Physicians, pharmacists and local public health offices offer vaccination services. Parents are encouraged to talk to their health care provider about recommended immunizations. Publicly-funded immunization schedules may vary between provinces and territories.

Do the benefits of immunization outweigh the risks?

YES. Vaccines are responsible for the control of many infectious diseases that were once common in this country and around the world, including polio, measles, diphtheria, pertussis (whooping cough), rubella (German measles), mumps, tetanus, and Haemophilus influenzae type b (Hib). Vaccine eradicated smallpox, one of the most devastating diseases in history. Over the years, vaccines have prevented countless cases of infectious diseases and saved literally millions of lives.

Since the introduction of vaccines, many serious illnesses have been brought under control. Immunization can protect you from:

  • blood infection
  • diphtheria
  • ear infection
  • Haemophilus influenzae type b (Hib)
  • hepatitis A
  • hepatitis B
  • Human Papilloma Virus (HPV)
  • influenza
  • measles (“red measles”)
  • meningitis
  • mumps
  • pertussis (whooping cough)
  • pneumonia
  • polio
  • rubella (“German measles”)
  • tetanus (lockjaw)
  • varicella (chicken pox)


Public Health Agency of Canada. Canadian Immunization Guide. Evergreen edition. (external link)

Canadian Paediatric Society (external link)