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Heart problems more common after Covid infection than vaccination, CDC reports


Compared to vaccination, Covid-19 itself is much more likely to lead to heart problems in teenagers and young men, the Centers for Disease Control and Prevention reported on Friday.

The study is the first to directly compare the odds of a type of heart inflammation called myocarditis following infection versus vaccination – providing a better understanding of the true risk of heart problems and possibly offering a comfort to parents and young men who have had questions about the risks and benefits of the vaccine.

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Myocarditis has long been linked to a variety of viruses, including influenza and coxsackieviruses. The condition was identified as a potential side effect of Covid mRNA vaccines in young people last summer.

At that time, the CDC found that cases of myocarditis were more than double what would normally be expected in men in their teens and early twenties who had been vaccinated. While Moderna and Pfizer-BioNTech vaccines have been linked to the problem, Pfizer’s vaccine is the only one authorized for people under 18.

Most cases of vaccine-related myocarditis have improved without any lasting problems, but the reports have left many parents worried, wondering if the potential heart risks of Covid vaccines in young men outweigh their benefits.

The new data, the doctors say, answers that question with a resounding no. This confirms what pediatric cardiologists have long noted in their patients: heart problems are much more likely to occur as a result of Covid than after vaccines.

“It absolutely mirrors what we’ve seen here,” Dr. Gerard Boyle, medical director of pediatric heart failure and transplant services at Cleveland Clinic Children’s Hospital, said of the new findings.

“The number of patients who came in with post-infection myocarditis far outnumbered the patients who came in with post-vaccination myocarditis – definitely,” he said.

In the study, researchers analyzed the electronic health records of more than 15 million people in 40 health systems nationwide, collected from January 2021 to the end of January 2022, looking for evidence of heart inflammation. or multisystem inflammatory syndrome in children. MIS-C causes inflammation around several organs, including the heart.

Overall, heart problems related to infection or vaccines were rare.

Rates of vaccine-related myocarditis, although uncommon, were highest in boys aged 12 to 17, particularly after their second dose of vaccine.

But even within this group, the risk of heart problems was up to 5.6 times higher after contracting Covid, compared to vaccination.

“These complications are quite rare,” said Dr. Matthew Oster, a physician at the CDC’s National Center for Birth Defects and Developmental Disabilities and author of the new report. “But if your question is, is my child at higher risk of having heart problems from catching Covid or from getting the vaccine, the answer is that they are at higher risk of having heart problems from Covid .”

Oster is also a pediatric cardiologist at Children’s Healthcare in Atlanta.

Common symptoms of myocarditis include chest pain and shortness of breath. Pediatric cardiologists have overwhelmingly stated that there is no evidence that young athletes are at greater risk for myocarditis than others.

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To reduce the risk of potential heart problems after vaccination, the CDC recently advised widening the gap between the first and second doses of mRNA vaccines at eight weeks. The move came after health experts in Canada determined that myocarditis rates dropped significantly when doses were separated by this range, rather than three to four.

The change makes sense for researchers such as Dr. Buddy Creech, a pediatric infectious disease expert at Vanderbilt University Medical Center in Nashville, Tennessee.

Creech, who is a principal investigator for the Moderna KidCOVE clinical trials, explained that side effects from the vaccine may be more likely to occur when the doses are too close together.

“It’s a real specific risk window,” he said. “We think what’s happening is there’s such an immune response to the vaccine in the hours and days after the second shot, that it triggers a stress reaction in the heart.” The body is on high alert during this time.

But giving the immune system more time to build strong, long-lasting responses may be key to reducing the risk of side effects, he said.

“If you give a second dose three or four weeks later, you’re at an immunological point where you have a lot of antibodies from that first dose, and now you’re giving a lot of antigen with the vaccine,” Creech said. noted.

The new data comes as vaccinations against Covid have lagged far behind in teenagers. According to the American Academy of Pediatrics, 14.4 million children between the ages of 12 and 17 have received two doses of the vaccine, representing just over half of children in this age group.

“I think people are still hesitant” to get their kids vaccinated, said Dr. Stuart Berger, a pediatric cardiologist at Lurie Children’s Hospital in Chicago. “But now we have real, concrete data that we can provide to them.”

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