Experts: mRNA COVID-19 vaccines likely tied to heart inflammation

Young black man getting vaccinated

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Today during a meeting of the Advisory Committee on Immunization Practices (ACIP), a panel of expert advisors to the Centers for Disease Control and Prevention (CDC), discussed rare instances of heart inflammation among mRNA COVID-19 vaccine recipients. The committee agreed the vaccines are likely linked to cases of myocarditis and pericarditis but said the benefits of vaccination outweigh the risks.

The first reports of myocarditis and pericarditis occurred in Israel in January, the experts said, and have followed in all countries using mRNAs. The myocarditis (inflammation of heart muscle) and pericarditis (inflammation of the tissues surrounding the heart) associated with vaccines are usually mild and respond well to a course of treatment with non-steroidal anti-inflammatories.

"Clinical presentation of myocarditis cases following vaccination has been distinct, occurring most often within 1 week after dose two, with chest pain as the most common presentation, " said Grace Lee, MD, chair of ACIP's safety subcommittee.

"mRNA vaccines may be a new trigger for myocarditis, yet it does have some different characteristics," said Matthew Oster, MD, MPH, from the CDC's COVID-19 Vaccine Task Force.

The most common symptoms reported by patients were chest pain, shortness of breath, and difficulty sleeping.

Cases mostly in males under 30

Tom Shimabukuro, MD, MPH, MBA, the deputy director of the Immunization Safety Office at the CDC, said the agency has received reports of 1,226 cases of myocarditis, with 827 (67.5%) reported after dose two of either the Moderna or Pfizer vaccine.

Of those cases identified after second doses, 563 followed the Pfizer vaccine series. In total, that's approximately 12.6 heart inflammation cases per million doses administered in the United States.

Among the 1,226 patients, 484 are younger than 29, and roughly two-thirds are men.

A major talking point through the ACIP meeting was that only Pfizer is approved for emergency use in the United States for teens ages 12 to 18. For this age-group, adenovirus-based vaccines, such as Johnson & Johnson, are not currently available.

Doran Fink, MD, PhD, deputy director-clinical, division of vaccines and related products applications at the Food and Drug Administration (FDA), said the agency would add warnings about the rare side effects on Moderna and Pfizer fact sheets. The CDC also said patients who develop heart inflammation after a first dose of mRNA should wait until their inflammation heals before getting a second dose, and should talk to their care providers.

Heart risks much higher with infection than vaccines

During the public comment, anti-vaccine advocates said no child or teen should be vaccinated against a disease that poses little serious threat to their lives.

Though the risk of death among teens who contract COVID-19 is small, the pandemic has made a dramatic impact on the lives of millions of teens and young adults across the country who have seen graduations, college plans, and jobs be put on hold for the last year. A new survey shows that nearly 80% of high school juniors and seniors say the pandemic has affected their plans after graduation, and 72% of 13- to 19-year-olds say they have struggled with their mental health, according to the New York Times.

In countries seeing a surge of new cases due to variants, young, unvaccinated adults represent a significant proportion of new cases, and public health experts have long said young adults and teens are conduits of COVID-19's community spread.

Today the Department of Health and Human Services (HHS) released a statement on ACIP's findings, saying myocarditis and pericarditis are much more common if a person contracts COVID-19 than from vaccination.

"Especially with the troubling Delta variant increasingly circulating, and more readily impacting younger people, the risks of being unvaccinated are far greater than any rare side effects from the vaccines," the HHS said. "Even if your infection is mild, you or your child could face long-term symptoms following COVID-19 infection such as neurological problems or diminished lung function."

In total, the CDC COVID Data Tracker shows that 379,446,660 COVID-19 vaccine doses have been delivered in the United States and 319,223,844 doses have been administered, with 150,426,657 Americans fully vaccinated (65.5% of adults have at least one dose).

Other US developments

  • Yesterday the United States reported 10,940 new COVID-19 cases and 370 deaths, according to the Johns Hopkins COVID-19 tracker.

  • In a briefing on Jun 21, Colorado's state epidemiologist said the Delta variant now accounts for 40% of the state's new COVID-19 cases, according to Fox News.

  • More than 150 healthcare workers who would not comply with the vaccine mandate at Houston's Methodist Hospital have resigned or been fired, the Washington Post reports. A federal judge upheld the mandate last week after workers filed a lawsuit.

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