Myocarditis and Pericarditis Following Vaccination with COVID-19 mRNA Vaccines in Ontario: December 13, 2020 to November 21, 2021: https://www.publichealthontario.ca/-/media/documents/ncov/epi/covid-19-myocarditis-pericarditis-vaccines-epi.pdf?sc_lang=en
Published: January 27, 2022 | Public Health Ontario

Quoting the original report — as of August 27, 2021 — which can be found here:
Myocarditis and Pericarditis Following Vaccination with COVID-19 mRNA Vaccines in Ontario: December 13, 2020 to August 7, 2021
https://web.archive.org/web/20210827194440/https://www.publichealthontario.ca/-/media/documents/ncov/epi/covid-19-myocarditis-pericarditis-vaccines-epi.pdf?sc_lang=en

There have been international reports, including from the United States and Israel, of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) associated with COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna vaccines).

The August 2021 report’s Table 1 (page 5) includes the following results for Ontario:

• 204 total cases
• 62 of these were after dose 1 and 142 of these were after dose 2
• Ages 12-17: 31 cases, Ages 18-24: 75, Ages 25-39: 54, Ages 40+: 44
• Pfizer-BioNTech: 100, Moderna: 104

The current (January 2022) report’s Table 1 (page 6) for Ontario includes the following results:

• 423 total cases
• 125 of these were after dose 1 and 298 of these were after dose 2
• Ages 12-17: 77 cases, Ages 18-24: 133, Ages 25-29: 49, Ages 30-39: 63, Ages 40+: 100
• Pfizer-BioNTech: 244, Moderna: 179