June 25, 2025
FDA Safety Communication
Purpose: To inform the public and healthcare providers that FDA has required and approved updates to the Prescribing Information for Comirnaty (COVID-19 Vaccine, mRNA) manufactured by Pfizer Inc. and Spikevax (COVID-19 Vaccine, mRNA) manufactured ModernaTX, Inc. to include new safety information about the risks of myocarditis and pericarditis following administration of mRNA COVID-19 vaccines. Specifically, FDA has required each manufacturer to update the warning about the risks of myocarditis and pericarditis to include information about (1) the estimated unadjusted incidence of myocarditis and/or pericarditis following administration of the 2023-2024 Formula of mRNA COVID-19 vaccines and (2) the results of a study that collected information on cardiac magnetic resonance imaging (cardiac MRI) in people who developed myocarditis after receiving an mRNA COVID-19 vaccine. FDA also required each manufacturer to describe the new safety information in the Adverse Reactions section of the Prescribing Information and in the Information for Recipients and Caregivers.
The Fact Sheets for Healthcare Providers and for Recipients and Caregivers for Moderna COVID-19 Vaccine and Pfizer-BioNTech COVID-19, which are authorized for emergency use in individuals 6 months through 11 years of age, have also been updated to include the new safety information in alignment with the Comirnaty and Spikevax Prescribing Information and Information for Recipients and Caregivers.
Updated Warning for Myocarditis and Pericarditis
The warning on myocarditis and pericarditis in the Prescribing Information for Comirnaty and Spikevax has been updated to convey that the observed risk of myocarditis and pericarditis following vaccination with mRNA COVID-19 vaccines has been highest in males 12 through 24 years of age and to include the following new language:
Based on analyses of commercial health insurance claims data from inpatient and outpatient settings, the estimated unadjusted incidence of myocarditis and/or pericarditis during the period 1 through 7 days following administration of the 2023-2024 Formula of mRNA COVID-19 vaccines was approximately 8 cases per million doses in individuals 6 months through 64 years of age and approximately 27 cases per million doses in males 12 through 24 years of age.
Follow-up information on cardiovascular outcomes in hospitalized patients who had been diagnosed with COVID-19 vaccine-associated myocarditis is available from a longitudinal retrospective observational study. Most of these patients had received a two-dose primary series of an mRNA COVID-19 vaccine prior to their diagnosis. In this study, at a median follow-up of approximately 5 months post-vaccination, persistence of abnormal cardiac magnetic resonance imaging (CMR) findings that are a marker for myocardial injury was common. The clinical and prognostic significance of these CMR findings is not known.
Information about myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining outside the heart) following vaccination with these mRNA COVID-19 vaccines has been included in the labeling since 2021. FDA closely monitors the safety of all vaccines, including the COVID-19 vaccines, during postmarket use.
About the Study on Cardiovascular Outcomes in mRNA COVID-19 Vaccine Recipients Diagnosed With Myocarditis
In a post-approval U.S. study funded and co-authored by FDA and published in September 2024, follow-up information was collected on approximately 300 people who developed myocarditis after receiving the original formula of an mRNA COVID-19 vaccine. Some people in the study reported having heart symptoms approximately 3 months after developing myocarditis. Some people in the study had cardiac MRIs (scans that show detailed images of the heart muscle) initially after developing myocarditis and again approximately 5 months later. The initial and follow-up cardiac MRIs commonly showed signs of injury to the heart muscle, with improvement over time in some but not all people. It is not known if these cardiac MRI findings might predict long-term heart effects of myocarditis.
Safety Monitoring Continues
Continuous monitoring and assessment of the safety of all vaccines, including the mRNA COVID-19 vaccines, is an FDA priority and we remain committed to informing the public when we learn new information about these vaccines.
In addition, as part of the approvals of Comirnaty and Spikevax, each manufacturer is required by FDA to conduct a study to assess if there are long-term heart effects in people who have had myocarditis after receiving an mRNA COVID-19 vaccine. These studies are underway.
How to Report a Suspected Adverse Event After Vaccination
Suspected adverse events may be reported to the Vaccine Adverse Event Reporting System (VAERS), which is co-managed by the FDA and the CDC.
