The reports represent just a tiny fraction of the nearly 130 million Americans who have been fully vaccinated with either Pfizer or Moderna’s doses.
“It’s a bit of an apples-to-oranges comparison because, again, these are preliminary reports. Not all these will turn out to be true myocarditis or pericarditis reports,” cautioned Dr. Tom Shimabukuro, a CDC vaccine safety official.
Shimabukuro said their findings were mostly “consistent” with reports of rare cases of heart inflammation that had been studied in Israel and reported from the U.S. Department of Defense earlier this year.
The CDC is working on more data and analysis on the reports ahead of the meeting of its own advisers, he said, and also planned to analyze the risk of heart inflammation posed by catching COVID-19.
The CDC first described the panel’s session as an “emergency meeting,” but later changed it to merely a “COVID-19 meeting.” Previous times the advisors convened to discuss the pandemic — like their May 12th gathering to mull recommendations for Pfizer’s COVID-19 vaccine in adolescents — were also described as “emergency meetings.”
The new details about myocarditis and pericarditis emerged first in presentations to a panel of independent advisers for the Food and Drug Administration, who are meeting Thursday to discuss how the regulator should approach emergency use authorization for using COVID-19 vaccines in younger children.
After earning an emergency use authorization for its COVID-19 vaccine in Americanslast month, Pfizer announced this week it had decided on doses to use in a clinical trial in children as young as 6 months old and hoped to submit data by October. Moderna said Thursday that it too had requested the FDA’s permission to give its mRNA vaccine to adolescents.
While Pfizer has said they expect to wrap up trials for children as young as 2 by September, FDA officials have previously cautioned that authorizing vaccines for these age groups could take longer — “mid to late fall” at the earliest — citing the additional follow-up data needed for children after they receive the shots.
“We recognize that some adverse reactions, for example myocarditis or pericarditis as discussed earlier today, may be too infrequent to detect in a safety database of typical size for pre-licensure clinical trials,” said Dr. Doran Fink, a top official in the FDA’s vaccine office.
The CDC previously disclosed that reports of heart inflammation were detected mostly in younger men and teenage boys following their second dose, and that there was a “higher number of observed than expected” cases in 16- to 24-year-olds. Last month, the CDC urged providers to “ask about prior COVID-19 vaccination” in patients with symptoms of heart inflammation.
“Risk-benefit considerations to determine whether to issue an emergency use authorization for use of a COVID-19 vaccine into healthy pediatric individuals will need to account for this information, and risk-benefit consideration will likely be different, not only compared to those for adults, but also they may be different for younger versus older pediatric groups,” Dr. Marion Gruber, director of the FDA’s vaccine office, said at the meeting.
Editor’s note: This story and headline have been updated to reflect that the CDC is now referring to Friday’s meeting as a “COVID-19 meeting” rather than an “emergency meeting.”