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Frequently Asked Questions

The questions and answers that follow are intended to assist in counselling about immunization; the wording and style are targeted at a general audience.

For vaccine questions specific to a particular disease, see the Vaccine-preventable Disease FAQs.

  1. What is a vaccination and how does it work?
  2. Do vaccines work?
  3. Are vaccines safe?
  4. How are vaccines made and licensed in Canada?
  5. Are there any reasons why someone should not be vaccinated?
  6. What would happen if we stopped immunizing?
  7. Why do we still need vaccines if the diseases they prevent have disappeared from our part of the world?
  8. Why can't I take a chance that my child won't get sick, as long as most other people are vaccinated?
  9. Do vaccines weaken the immune system?
  10. Can giving a child several vaccines at the same time overload the immune system?
  11. Can natural infection or a healthy lifestyle be effective alternatives to vaccines?
  12. Why do we need vaccines if we have better hygiene and sanitation to help prevent disease in Canada?
  13. What about reports that vaccines are linked to chronic diseases or problems such as sudden infant death syndrome (SIDS)?
  14. Do vaccines contain toxic ingredients?
  15. Can vaccines transmit animal disease to people?
  16. Is immunization compulsory in Canada? Does my child have to be immunized?
  17. Where can I get vaccinated and do I have to pay?
  18. Will my child have a reaction?
  19. Aside from following the routine childhood immunization schedule, are there any other vaccines or shots my child should get?
  20. I've heard that MMR (measles-mumps-rubella) vaccine can cause autism. Is that true?
  21. I've heard that thimerosol can cause autism. Is that true?
  22. What are the recommended vaccines for children?

Key messages on vaccine safety in Canada

  • The vaccines used in Canada are highly effective and extremely safe.
  • Serious adverse reactions are rare. The dangers of vaccine-preventable diseases are many times greater than the risks of a serious adverse reaction to the vaccine.
  • Health authorities worldwide take vaccine safety very seriously. Expert committees in Canada investigate reports of serious adverse events.
  • There is no evidence that vaccines cause chronic diseases, autism or sudden infant death syndrome. Alleged links - for example between hepatitis B vaccine and multiple sclerosis - have been disproved by rigorous scientific study.