Unlike some countries, immunization is not mandatory in Canada; it cannot be made mandatory because of the Canadian Constitution. Three provinces require proof of immunization for school entrance: . . . But, exceptions are permitted on medical or religious grounds and reasons of conscience; legislation and regulations must not be interpreted to imply compulsory immunization.
—Canada Communicable Disease Report, May, 1997; Vol 23S4. Supplement: Canadian National Report on Immunization; 1996. Go to page 3, Chapter 1: “Immunization in Canada”
Click https://publications.gc.ca/collections/collection_2016/aspc-phac/HP3-1-23-S4-eng.pdf and then click “Continue to Publication” (I can open PDF from Firefox when it’s set to open inside the browser).
Listed here: https://publications.gc.ca/site/eng/9.507730/publication.html), click on “1997 Click to Expand.” Click on “Vol. .23;S.4:May 1997 HP3-1-23-S4-eng.pdf (PDF, 9.17 MB).”
More details in that PDF and at vaccinechoicecanada/exemptions/.