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The benefits of Covid-19 vaccination far outweigh the risks of heart inflammation in young people, a panel of independent advisers to the Centers for Disease Control and Prevention said Wednesday.
Still, members of the group, called the Advisory Committee on Immunization Practices, agreed that a warning about the potential risk should be added to the Food and Drug Administration's official fact sheets on the vaccines.
The mRNA Covid-19 vaccines can, in rare instances, be linked to inflammation of the heart or surrounding tissue, called myocarditis or pericarditis. More than 300 cases have been confirmed by the CDC in adolescents or young adults — a figure that’s higher than what would usually be expected. The mRNA vaccines are made by both Pfizer-BioNTech and Moderna.
But the risk of Covid-19 is far higher: Teens and young adults account for the largest proportion of new cases in the United States, Dr. Megan Wallace, of the CDC’s National Center for Immunization and Respiratory Diseases, said during a presentation to the agency’s Advisory Committee on Immunization Practices. Since the beginning of the pandemic, there have been 2,767 Covid-19 deaths among people ages 12-29, with 315 deaths reported in that age group since April 1, according to CDC data presented at the meeting.
“The benefits certainly, at this time, outweigh the potential risks,” said advisory committee member Dr. Pablo Sanchez, a professor of pediatrics at Ohio State University.
But, he added, “we need to be very upfront, in terms of mentioning this as a potential risk” and make sure that parents and patients are aware of the risk before vaccination.
The CDC also presented vaccination guidance for people who have previously had myocarditis. For past myocarditis unrelated to vaccination, people can receive the Covid-19, as long as their symptoms have resolved. People who developed the condition after the first dose of the vaccine, however, should not receive the second dose at this time.
The advisory group convened as cases of the highly contagious delta variant, first detected in India, continue to spread in the U.S. Delta cases now make up 20 percent of new Covid-19 cases. All available vaccines are effective against the variant.
Myocarditis cases were most common in males in their teens and early 20s, and were mostly to occur within one week after the second dose. The most common symptom was chest pain, followed by shortness of breath.
Myocarditis after Covid-19 vaccination is “still a rare event,” Dr. Tom Shimabukuro, deputy director of the CDC's Immunization Safety Office, said during the meeting. It occurs at a rate of about 12 cases per million second dose vaccinations in people ages 39 and younger, he said.
As of June 11, 323 cases in people ages 29 and younger have been confirmed by the CDC. Another 148 cases are under review.
Of the confirmed cases, 309 were hospitalized and, for those for whom outcome data is available, 295 have been discharged. Nine remain in the hospital, with two people in intensive care units. Fourteen people were only seen in outpatient settings.
The Advisory Committee on Immunization Practices presentations underscored that the vast majority of patients have recovered, though more data on the long-term effects are needed.
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Myocarditis is a broad term that means inflammation of the heart muscle. It does not have one single cause.
“You can have inflammation of the heart for multiple reasons,” said Dr. Katie Passaretti, medical director for infection prevention at Atrium Health in Charlotte, North Carolina. “The most common is after you have a viral infection.” Passeretti is not a member of the advisory committee.
Viral myocarditis can be very serious, Dr. Paul Offit, a vaccine researcher at the Children's Hospital of Philadelphia, said. But the cases linked to Covid-19 vaccination are not caused by a viral infection and appear to be “much more mild and transient.”
But “the minute you say ‘myocarditis,’ the minute you say ‘heart muscle inflammation,’ you can say 'mild,' 'transient' 'short-lived' and 'self-resolving' as many times as you want, that's not how people are going to hear this,” Offit, who is also not a member of the advisory committee, said. “They're going to hear this as something really bad because myocarditis typically is really bad, it's just not this kind of myocarditis.”
“We use the same word here, myocarditis, even though the pathogenesis is clearly different,” he added.
Indeed, the cases that have so far been observed after Covid-19 vaccination have, for the most part, been less severe than myocarditis from other causes, Dr. Matthew Oster, a member of the CDC’s Covid-19 Vaccine Task Force, said during the advisory committee meeting. Patients are in the hospital for a shorter amount of time and require less treatment, he said.
Symptoms can include fever, fatigue, shortness of breath and chest pain especially when leaning forward.
When needed, treatment may involve anti-inflammatory drugs, such as ibuprofen, and in some cases, an intravenous medication called IVIG.