Overview
- Pfizer compiled evidence from large U.S., U.K., French and Nordic datasets and a meta-analysis, finding post‑vaccination myocarditis to be very rare, with England data on more than 42 million shots showing a lower risk of hospitalization or death than after infection.
- The highest observed rates occur in young males within roughly 14 days after the second primary dose, with CDC VAERS analyses indicating boosters carry a lower incidence.
- A systematic review cited by the company estimated the myocarditis risk after Covid infection to be about 42 times higher than after vaccination.
- Follow‑up studies suggest a favorable clinical course for vaccine‑associated cases, including French national data showing fewer cardiovascular complications than conventional myocarditis.
- Outcome cohorts reported no heart‑related deaths or transplants in an FDA‑funded study of 333 cases over a median 178 days and no deaths with improving quality of life in an Australian 18‑month study of 256 cases.