Moderna Covid vaccine for teens awaits approval as regulators reassess heart inflammation risk

A healthcare worker fills a syringe with Moderna COVID-19 vaccine.

Ben Hastie | MediaNews Group | Getty Images

For months, approval of Moderna’s Covid-19 vaccine for teens has been put on hold as the Food and Drug Administration considers the risk of a rare but serious form of heart inflammation that mostly affects young people who have been vaccinated by the company or Pfizer. .

Moderna applied for emergency approval for its Covid vaccine for children aged 12 to 17 in June, but the FDA told the company in October that it would not complete testing of the vaccine for children until January.

The agency said it needed more time to study the risk of myocarditis in vaccines based on mRNA technology, which is used in both companies’ vaccines. The FDA, in a statement to CNBC on Wednesday, said it was conducting the review as quickly as possible but could not predict how long the evaluation would take. The agency said the review is intended to make sure the benefits of the vaccine outweigh the risks for teens.

Messenger RNA or mRNA vaccines use the genetic code to teach cells to make a protein that triggers an immune response if someone gets infected with the virus. Traditional vaccines, such as the Johnson and Johnson vaccines, introduce inactivated microbes into our bodies.

The FDA fully approved Moderna’s two-dose adult vaccine on Monday, and the Centers for Disease Control and Prevention is expected to give its final approval shortly. Its committee of vaccine experts meets on Friday to review the latest data on myocarditis in adolescents and adults.


In October, Moderna said it would wait to ask the FDA to approve its vaccine for children ages 6 to 11 until a vaccine for teens gets the green light. The company expects to release data on its vaccine for children aged 2 to 5 in March.

Myocarditis is an inflammation of the heart muscle that can lead to serious health problems, according to the National Heart, Lung, and Blood Institute. Viral infections are the most common cause of myocarditis. According to the Department of Health and Human Services, people are much more likely to get myocarditis from Covid than from vaccines, and the risk to the heart may be more severe.

According to a recent article in the journal Nature Reviews Cardiology, the risk of myocarditis from Covid is 100 times higher than the risk of developing the disease after vaccination. According to the study, the risk of death from Covid-related myocarditis is between 20% and 70%, while the risk of death from myocarditis due to vaccination is less than 1%.

Dr. Jose Romero, former chair of the CDC’s independent vaccine expert committee, said vaccine-associated myocarditis is usually mild and resolves quickly.

Myocarditis from Covid

“While Covid-induced myocarditis is more severe, lasts longer, and the mortality rate can be significant,” said Romero, who serves as health secretary in Arkansas.

Children are more likely to suffer from a multisystem inflammatory syndrome known as MIS-C after contracting Covid than from vaccine-induced myocarditis. Since the start of the pandemic, more than 6,000 children have developed MIS-C. MIS-C often affects the heart and can lead to myocarditis and other cardiac complications. At least 55 children have died from MIS-C, according to the CDC.

Dr. Matthew Auster, pediatric cardiologist at Children’s Healthcare of Atlanta, said MIS-C is much more common and more severe in children than vaccine-induced myocarditis. Children’s of Atlanta hospitalized 13 children with myocarditis after vaccination, compared with more than 400 children hospitalized with MIS-C, Oster said.

“We have more than half of them requiring intensive care unit stays,” Oster, director of the Pediatric Heart Disease Research Program, said of children hospitalized with MIS-C. “We have more than half of them requiring a stay in the intensive care unit. It’s much more common and much more severe than myocarditis from vaccination.”

French and Scandinavian studies

In the fall, Moderna’s vaccine for teenagers came under closer scrutiny. French and Scandinavian studies have found an increased incidence of myocarditis after a second dose of Moderna vaccine in adolescents and young adult men than after the Pfizer vaccine. according to the European Medicines Agency. However, the European Union’s lead medicines agency said the benefits of both vaccines outweigh the risks, as myocarditis is a rare side effect. Sweden and other Nordic countries are limited using Moderna for youth in October. Canada also found to be at higher risk.

Moderna said in October that the company had not observed an increased risk of myocarditis in people under 18 years of age. However, the company said it is conducting its own external data review and intends to work closely with the FDA to support the agency’s assessment. Romero said the FDA did the right thing by waiting and gathering as much data as possible before making any decisions.

When Moderna petitioned the FDA in early June to lower the age limit for its vaccine to teenagers 12 to 17 years old, CDCn began receiving reports of myocarditis in young men who had received the Pfizer vaccine. The CDC just recommended the Pfizer vaccine for children ages 12 to 15 in May. Pfizer and Moderna vaccines use mRNA technology.

Link to mRNA vaccines

Short hospital stay

Oster, one of the authors of the study, said hospital stays were short and children often recovered after taking pain medication.

“We recommend that those who have it refrain from active physical activity for a few months just to make sure the heart has fully recovered, but we see people recovering and so far the long-term results have looked good,” Oster said. .

Young males aged 16 to 17 reported the highest rates of myocarditis after the second dose of Pfizer vaccine, about 106 per 1 million doses administered, while boys aged 12 to 15 reported 71 per million doses administered. according to research. Oster said traditional myocarditis is also more common in male adolescents.

Researchers are still learning what causes myocarditis after vaccination, and many scientists suggest that testosterone may play a role. Although Pfizer and Moderna are two-dose vaccines, the 30 mcg Pfizer dose for everyone over 12 years of age is lower than the 100 mcg dose Moderna uses for teenagers. However, Romero cautioned against drawing conclusions based on the dosage of the two mRNA vaccines, as they have other differences as well. They use various fat vesicles, for example, to deliver mRNA material to cells, which then begin to produce proteins that trigger an immune response to protect against the virus.

Dr. Sean O’Leary, vice chairman of the American Academy of Pediatrics Committee on Infectious Diseases, said parents need to know that the decisions they make every day, such as driving, carry a higher risk than developing myocarditis in their child. after vaccination. According to him, the risk of Covid disease is much higher than the risk of a vaccine.

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