A general view of the U.S. Centers for Disease Control and Prevention (CDC) headquarters in Atlanta, Georgia September 30, 2014. REUTERS/Tami Chappell/File Photo
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 U.S. Centers for Disease Control and Prevention (CDC) said on Thursday.
More than half of the myocarditis or pericarditis cases reported to the U.S. Vaccine Adverse Event Reporting System after patients had received either the Pfizer/BioNTech (PFE.N), or Moderna (MRNA.O) vaccines were in people between the ages of 12 and 24, the CDC said. Those age groups accounted for less that 9% 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 U.S. Food and Drug Administration that is meeting on Thursday.