More than 1,200 cases of heart inflammation have been reported in people who received COVID-19 vaccines produced by Pfizer and BioNTech or by Moderna, according to the Centers for Disease Control and Prevention.

       The figure was reported Wednesday at a meeting of the CDC’s Advisory Committee on Immunization Practices, which is weighing heart risks from the vaccines, particularly in adolescents.

       More than 130 million Americans have been fully vaccinated with one of the two vaccines, both of which are made using mRNA technology. Despite their widespread use, there have been few reports of serious adverse effects.

       In May, the Pfizer-BioNTech shot was cleared for emergency use in people as young as 12 after earlier being authorized for those 16 and older. About 20% of adolescents ages 12 to 15 are now fully vaccinated, according to the CDC.

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       Initial safety findings from the U.S. health agency suggest real-world data is consistent with the results from the companies’ clinical trial prior to authorization.

       The risk of heart inflammation, or myocarditis, following vaccination is notably higher a few days after the second dose. It’s also higher in male adolescents and young adults who are at least 16.

       More data are needed to understand risk factors, treatment and long-term outcomes, members of the advisory committee said.

       Since April, the CDC has seen a spike in reports of myocarditis along with pericarditis, an inflammation of the membrane around the heart. The cases, while rare, have occurred mostly in male teens and young adults.

       “We’re observing this in younger age groups, mainly teens and early 20s,” Dr. Tom Shimabukuro, deputy director of the CDC’s Immunization Safety Office, said at the ACIP meeting. “This largely disappears when you get to older age groups.”

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       Some vaccine experts having second thoughts about rushing to inoculate kids

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       Some vaccine experts having second thoughts about rushing to inoculate kids

       A growing contingent of medical experts is questioning the conventional wisdom that healthy children should get COVID-19 shots as soon as possible.

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       Still, CDC Director Dr. Rochelle Walensky said Wednesday that mRNA vaccines have been successful in preventing severe illness and death among young people.

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       Speaking at the Milken Institute Future of Health Summit, Walensky added that the data presented at the advisory committee meeting will “overwhelmingly demonstrate that the benefits of vaccination far outweigh the risks.”

       In a joint statement, the CDC, leaders of the American Academy of Pediatrics, the American Medical Assn., the American Heart Assn. and a host of other medical and public health groups strongly endorsed continued use of the COVID-19 vaccines despite the reports of myocarditis.

       “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,” the statement said.

       “In addition, we know that myocarditis and pericarditis are much more common if you get COVID-19, and the risks to the heart from COVID-19 infection can be more severe.”