That’s a contributing factor, yes

https://www.cbc.ca/news/health/measles-vaccination-coverage-1.7525234

In Ontario and New Brunswick, parents and caregivers are required to report student vaccine records to public health to enforce legislation like the Immunization of School Pupils Act. The act requires proof of immunization for students to attend school, with exceptions just for medical or ideological reasons.

During the height of COVID, Oda said limits on in-person appointments and the diversion of health care resources away from preventative care like immunization created barriers to routine childhood vaccinations. Now, lack of access to primary care providers continues to limit vaccinations even for willing families, she said.

Sorry, didn’t answer you, not required, but it causes people to not get vaccinated.