The headquarters of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.
Tami Chapel | Reuters
A CDC safety group said there was a “likely link” between rare heart inflammation in adolescents and young adults, mostly after they received their second Covid-19 vaccine, citing the latest available data.
There have been more than 1,200 cases of myocarditis or pericarditis, mostly in those under the age of 30 who Pfizer‘s or Modern ”s Covid vaccine, according to a series of slide presentations released Wednesday for a meeting of the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention.
Myocarditis is the inflammation of the heart muscle while pericarditis is the inflammation of the membrane that surrounds the heart.
“The clinical picture of myocarditis cases after vaccination was variable and most often appeared within a week of the second dose, with chest pain being the most common,” said Dr. Grace Lee, Chair of the Committee’s Security Group. CDC officials are collecting more data to fully understand the potential risks, how to deal with them and if there are any long-term issues, she said.
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The agency said 267 cases of myocarditis or pericarditis were reported after receiving one dose of the mRNA vaccines and 827 cases after two doses by June 11. There are 132 additional cases where the number of doses received is unknown, the CDC said.
The agency announced that around 300 million shots had been administered by June 11.
“This is still a rare occurrence,” said Dr. Tom Shimabukuro at the meeting. For both vaccines combined, there were 12.6 cases of heart inflammation per million doses. Cases were more common among Moderna vaccine recipients at 19.8 cases per million than eight cases per million at Pfizer, he said.
Men under 30 make up the bulk of cases, the CDC said, and most cases appear to be mild. Of the 295 people who developed the disease and were discharged, 79% made a full recovery, according to the presentation. Nine people were hospitalized, according to the agency, two of them in the intensive care unit.
CDC officials said the benefits of the Covid vaccine still outweigh the risks.
Cases in younger people are increasing as older people are vaccinated at higher rates. The US vaccinated 177.6 million people with at least one dose, according to the CDC, that’s about 53% of the population. Only 13.6% of 18- to 24-year-olds in the United States received at least one dose of vaccine, compared with 26% of people ages 50 to 64, the data shows.
While hospitalization rates have decreased in older age groups, they have barely moved in adolescents and young adults, said Dr. Megan Wallace from the CDC.
“Teenagers and young adults make up a larger proportion of the total cases, 33% of the cases reported in May were people ages 12-29, compared with 28% last December,” she said. Since the pandemic began, 2,767 people aged 12 to 29 have died of Covid, she said, noting that 316 of these deaths had occurred since April 1.
The CDC is coordinating its investigation with the Food and Drug Administration, which last month the PfizerBioNTech Vaccine for adolescents aged 12 to 15 years. Symptoms, which include chest pain and shortness of breath, typically develop within a week of receiving the vaccination, with most developing within four days, the agency said.
This is a developing story. Please check again for updates.
CNBC’s Rich Mendez contributed to this article.
Correction: Most of the cases of people who had myocarditis occurred in people under the age of 30. In a previous version, the age was incorrectly stated. The number of cases per million doses administered was 12.6. In an earlier version, the number was incorrectly specified.