The US Food and Drug Administration (FDA) on Friday added a warning to the documentation accompanying the COVID-19 vaccines developed by Pfizer/BioNTech and Moderna to indicate the rare risk of heart inflammation after their use.
For each vaccine, the provider information sheets have been revised to include that the adverse events noted suggest an increased risk of myocarditis and pericarditis, particularly after the second dose and with onset of symptoms within a few days of vaccination, the FDA said.
As of 11 June, more than 1,200 cases of myocarditis or pericarditis have been reported to the US Vaccine Adverse Event Reporting System (VAERS), out of approximately 300 million doses of messenger RNA vaccine administered.
Cases appear to be significantly higher in men and within one week of the second dose of vaccine. The US Centers for Disease Control and Prevention (CDC) has identified 309 hospital admissions due to heart inflammation in people under 30 years of age, of which 295 were discharged from hospital.
Health authorities in several countries have investigated cases of myocarditis and pericarditis, most commonly seen in young men, after an injection of Pfizer or Moderna.
The FDA’s latest update follows a thorough review of the information and a meeting of the CDC’s Advisory Committee on Immunisation Practices.
Pfizer and Moderna did not immediately respond to requests for comment.