Pfizer releases global myocarditis data for covid-19 vaccinated children — Children vaccinating immunization concept. Doctor injecting vaccination in arm of a little girl with face mask.

NEW YORK, N.Y. – Pfizer Inc. on Monday released detailed analyses of myocarditis cases linked to its COVID-19 vaccine, Comirnaty, emphasizing that the condition remains an uncommon side effect and that the overall benefits of vaccination continue to outweigh the risks.

The company said the data—collected from large-scale studies across multiple countries—was published in peer-reviewed journals and shared on Pfizer’s COVID-19 research hub.

Pfizer officials said the new disclosures reflect the company’s ongoing commitment to transparency and vaccine safety monitoring.

Myocarditis risk remains low across global studies

Pfizer’s analysis reaffirmed that myocarditis, an inflammation of the heart muscle, occurs infrequently after vaccination with mRNA-based COVID-19 vaccines. Studies from the United States, France, the Nordic countries, and the United Kingdom show the highest incidence among young males within two weeks after receiving a second dose.

The data also show that myocarditis following a booster dose is less common than after the second primary dose. The findings were consistent with results reported by the U.S. Centers for Disease Control and Prevention through its Vaccine Adverse Event Reporting System.

Infection poses far greater myocarditis risk than vaccination

Pfizer highlighted a meta-analysis showing that the risk of myocarditis after COVID-19 infection is roughly 42 times higher than after vaccination. The company noted that vaccine-associated myocarditis generally presents milder symptoms and has better clinical outcomes than myocarditis caused by infection or other conditions.

A French cohort study following patients for 18 months found that individuals who developed myocarditis after vaccination experienced fewer cardiovascular complications than those with traditional myocarditis.

Long-term studies show positive recovery outcomes

Further evidence from more than 42 million vaccinations in England revealed that the risk of hospitalization or death due to myocarditis remains small even after multiple vaccine doses. A U.S. Food and Drug Administration–funded study of 333 cases found no cardiac-related deaths or need for heart transplants after six months.

An 18-month follow-up study in Australia of 256 individuals with vaccine-associated myocarditis reported no deaths, few hospitalizations, and gradual improvement in overall health outcomes.

Pfizer reaffirms commitment to transparency and monitoring

Chief Scientific Officer Chris Boshoff said ongoing monitoring and public reporting are central to Pfizer’s safety strategy. “Our commitment to rigorous safety protocols and open communication ensures we maintain the confidence of patients, health authorities, and the public,” Boshoff said.

Pfizer stated that myocarditis remains a rare event and that all new data will continue to be shared promptly with regulators and the public.

Pfizer’s latest report underscores that while myocarditis cases are being closely monitored, COVID-19 infection still carries a far higher risk of heart inflammation than vaccination.

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