There's a "likely association" between rare heart inflammation and Pfizer and Moderna's mRNA COVID-19 vaccines among adolescent and young adult recipients, the CDC's Advisory Committee on Immunization Practices said during a June 23 meeting.
As of June 11, 1,226 cases of myocarditis, heart muscle inflammation, or pericarditis, inflammation of the heart muscle lining, have been reported to the CDC's national Vaccine Adverse Event Reporting System, according to slides presented during the meeting.
Eight more notes:
1. Reports of heart inflammation were mostly among people ages 30 and younger, and mostly occurred within one week after the second dose of mRNA vaccine.
2. Most cases occurred among men and have been mild. Chest pain has been the most common symptom.
3. There have been 323 such cases among people younger than 29 — the age group for which the CDC's investigation is particularly focused on.
4. Among 295 people with heart inflammation who've been discharged, 79 percent have fully recovered. As of June 11, nine people were still hospitalized, with two people in the intensive care unit.
5. For both vaccines, there have been 12.6 cases of heart inflammation per million doses. For Moderna's vaccine, that number is 19.8 cases per million doses, compared to 8 cases per million for Pfizer's vaccine.
6. Officials from the panel highlighted that 300 million mRNA shots had been administered as of June 11 in the U.S. "This is still a rare event," said Tom Shimabukuro, MD, of the agency's vaccine safety team.
7. The CDC is continuing to work with the FDA on the investigation, which authorized Pfizer's vaccine for use among children ages 12-15 in May. The agency is continuing to conduct follow-up on vaccine-associated cases to assess longer-term outcomes.
8. Following the June 23 meeting, the CDC, HHS, and a number of other U.S. medical groups issued a joint statement emphasizing the benefits outweigh the risk of potential harm. "The facts are clear: this is an extremely rare side effect, and only an exceedingly small number of people will experience it after vaccination. Importantly, for the young people who do, most cases are mild, and individuals recover often on their own or with minimal treatment. In addition, we know that myocarditis and pericarditis are much more common if you get COVID-19, and the risks from COVID-19 infection can be more severe."
The meeting comes after the committee said June 10 it had received 275 reports of heart inflammation among people ages 16-24 after their second dose of mRNA vaccine.