Jun 11, 2021 06:00 UTC
  • Heart inflammation cases in young men higher than expected after mRNA vaccine shots

Preliminary findings from two vaccine safety monitoring systems suggest a higher-than-expected number of cases of heart inflammation after the second dose of mRNA COVID-19 vaccines in young men, the US Centers for Disease Control and Prevention (CDC) said on Thursday.

More than half of the myocarditis or pericarditis cases reported to the US Vaccine Adverse Event Reporting System after patients had received either the Pfizer/BioNTech or Moderna vaccines were in people between the ages of 12 and 24, the CDC said. Those age groups accounted for less than 9 percent of the doses administered.

"We clearly have an imbalance there," Dr. Tom Shimabukuro, deputy director of the CDC's Immunization Safety Office, said in a presentation to an advisory committee to the US Food and Drug Administration that is meeting on Thursday.

He said that the Vaccine Safety Datalink (VSD) – another safety monitoring system - showed an increased incidence of heart inflammation in 16 to 39-year-olds after their second dose of the shots when compared to the rate observed after their first dose.

The limited data shows that most of the patients - at least 81 percent of them - had a full recovery from their symptoms, Shimabukuro said.

Pfizer and Moderna were not immediately available for comment.

The CDC said it will hold a meeting of its Advisory Committee on Immunization Practices next week to further evaluate the evidence and assess the risk of myocarditis following mRNA vaccination for COVID-19.

MG

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