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Heart Inflammation Rate After Second COVID Vaccine Is 16 in a Million: CDC

Newsweek logo Newsweek 6/11/2021 Ed Browne
a close up of a person holding a cell phone: A pharmacist administers a Moderna COVID-19 vaccine in Seattle, Washington, in December 2020. Further evaluation of myocarditis reports is ongoing, the CDC has said. © Karen Ducey/Getty A pharmacist administers a Moderna COVID-19 vaccine in Seattle, Washington, in December 2020. Further evaluation of myocarditis reports is ongoing, the CDC has said.

The U.S. Centers for Disease Control and Prevention (CDC) has said it is going to hold a meeting to discuss rare reports of heart inflammation, or myocarditis/pericarditis, in COVID vaccine patients.

The news follows a meeting of the Vaccines and Related Biological Products Advisory Committee on Thursday, in which data showed that as of May 31, there have been a total of 216 reports of the condition after the first dose of either Pfizer or Moderna vaccines. There were 573 reports after the second dose.


The CDC notes that at least 81 percent of discharged patients aged 30 and under made a full recovery, according to limited outcome data.

It should also be noted that these few heart inflammation cases have arisen out of more than 165 million people who had received at least one dose of a COVID vaccine at the time the data was collected, highlighting their rarity.

The committee report notes that early Vaccine Safety Datalink suggests reports of heart inflammation cases are at a rate of 16 per million second COVID vaccine doses.

The condition was reported in men more often than in women, and the median age of those affected was 30 after the first dose, and 24 after the second.

Focusing on patients aged 30 or under, the report said 226 cases met the CDC's "working case definition," and that further investigation is ongoing for the remaining reports.

Researchers were also able to track 285 of the cases to see how patients recovered. At the time of the report 270 were discharged from hospital and 15 remained in hospital—three in intensive care.

Video: CDC: Heart inflammation in young men higher than expected after Pfizer, Moderna vaccines (Yahoo! News)

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Of those who were discharged, 180 had made full recoveries while 41 were either still showing some symptoms or had an unknown status.

The CDC's Advisory Committee on Immunization Practices (ACIP) is due to hold a virtual meeting on June 18, starting 11 a.m. EDT, to further discuss cases of myocarditis as well as general vaccine safety.

At the time of writing 141,583,252 people have been fully vaccinated against COVID in the U.S.—42.6 percent of the total population.

Dr. Tom Shimabukuro, a CDC vaccine safety official who presented the myocarditis data Thursday, told CBS the reports are only preliminary and "not all of these will turn out to be myocarditis or pericarditis reports."

As it is, the preliminary data suggests the heart inflammation cases are occurring more than would be generally expected in people aged 24 and under, but not necessarily for people older than that.

The reports were found using the U.S. VAERS database—the national early warning system designed to detect possible safety problems with vaccines. It is useful for detecting patterns, but it is not designed to determine if a vaccine actually caused a reported health problem.

Myocarditis is inflammation of the heart muscle. Pericarditis is inflammation of the tissue that forms a sac around the heart. Both can cause chest pain, fever, and shortness of breath.

Causes of heart inflammation include infections, medical conditions that damage the heart, and some medicines, according to the National Heart, Lung, and Blood Institute (NHLBI).

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