Measles is a very contagious childhood disease, but the vaccines are very effective, to the extent that the elimination of measles is now a global priority. It is really important for people to keep up to date with the vaccination. It may have been delayed due to COVID itself, so it's really important to catch up. The provinces and territories are, in fact, responsible for any of those vaccine policies.
In Canada, there's no specific mandating of measles vaccination, but jurisdictions vary in their requirements. Some require the provision of measles vaccination status for school entry, for example, but that is not within the federal jurisdiction.