Experts have found a potential link between heart inflammation and COVID-19 vaccines in young adults. Here's what to know about the possible connection—and why experts recommend that everyone 12 and older still get vaccinated.

Advertisement

About 15 months into the coronavirus pandemic, 179 million Americans have received at least one dose of the COVID-19 vaccine. The vast majority report mild side effects like injection site pain, body aches, and low-grade fever. But experts have recently noticed a rare symptom in a very small percentage of young people who received Pfizer or Moderna: an inflammation of the heart muscle called myocarditis.

"We're seeing an uptick in the amount of myocarditis cases diagnosed, especially in people under 30," says Steven Abelowitz, M.D. FAAP, a board-certified pediatrician who serves as the medical director and president of Coastal Kids pediatric medical group. He adds most myocarditis cases have occurred in males between the ages of 16 and 24-usually several days after the second dose of the mRNA vaccine. 

Vaccine or flu shot in injection needle. Doctor working with patient's arm. Physician or nurse giving vaccination and immunity to virus, influenza or HPV with syringe.
Credit: Getty Images

Myocarditis after vaccination appears rare; slightly more than 1,200 cases have been reported across all age groups through June 11, though not all have been confirmed, according a presentation by the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices. Plus, "most of the cases are short-lived and mild," adds Dr. Abelowitz. "About 80 percent of people hospitalized are recovering fully and going home."

The Food and Drug Administration (FDA) recently added a warning about myocarditis and pericarditis to the "patient and provider fact sheets" for Pfizer and Moderna. Even so, the FDA and CDC still advise that everyone 12 and up receive their COVID-19 vaccine. The potential consequences of the coronavirus (including long-term health problems, hospitalization, and death) far outweigh the risk of myocarditis after vaccination.

Here's everything you need to know about the possible link between myocarditis and COVID-19 vaccines.

What is Myocarditis? 

Myocarditis is an inflammation of the heart muscle. "This inflammation enlarges and weakens the heart, creates scar tissue, and forces it to work harder to circulate blood and oxygen throughout the body," according to the Myocarditis Foundation. While it's most commonly caused by viral infections, it can also be triggered by medications, autoimmune disease, environmental toxins, or other factors. 

Myocarditis is a relatively uncommon condition, even before it was linked to the COVID-19 vaccine. "You probably see one or two cases per year in pediatric offices," adds Daniel Cohen, M.D. a pediatrician at Westmed Medical Group. It mainly occurs between puberty and the early 30's, and it generally affects males more than females.

Thankfully, myocarditis usually isn't serious. Most individuals have no symptoms and aren't diagnosed at all, according to the Myocarditis Foundation. That said, if symptoms are present, they can include chest pain that worsens after exertion or lying down, rapid heartbeat, shortness of breath, fever, fatigue, lightheadedness, and fainting. In extreme cases, myocarditis can lead to abnormal heartbeat, heart failure, or death (although this isn't common).

Treatment of myocarditis varies for everyone. Many patients get better without intervention, but doctors may also prescribe anti-inflammatory medications or steroids.

Note that myocarditis is different from pericarditis, which is a "inflammation of the outer lining of the heart," says the CDC. Some cases of pericarditis have also been reported in young people who received the Pfizer or Moderna COVID-19 vaccines.

Is There a Link Between Myocarditis and COVID-19 Vaccines?

When it comes to myocarditis after COVID-19 vaccines, "it's more of a numbers situation," explains Dr. Abelowitz. Experts first became concerned after data from the Vaccine Adverse Event Reporting System (VAERS)-a repository of reports from patients and professionals about vaccine side effects-showed higher-than-expected cases of myocarditis or pericarditis in vaccinated individuals under 30 years old.

Indeed, VAERS data compiled through May 31 depicted 789 cases of suspected myocarditis or pericarditis after vaccination in people of all ages. Digging a little deeper, 475 of the reported cases happened in people under the age of 30-and about 226 of them were confirmed (the CDC is conducting follow-up and review of the remaining cases).

Perhaps the most concerning for experts, 196 of the myocarditis/pericarditis reports were in young adults between the ages of 18 to 24, while 79 cases were among 16- to 17-year-olds. These are surprisingly high numbers, says the American Heart Association (AHA), considering people under 24 years old account for only 9 percent of all vaccinations in America. 

The CDC also reported on outcomes for these individuals. Of the 475 people under 30 with suspected myocarditis or pericarditis, they have information for 285 of them. The majority (270 people) were discharged, while 15 remained in the hospital (with three in the intensive care unit). Additionally, 81 percent had "full recovery of symptoms," and 19 percent had "ongoing signs or symptoms or unknown status," says the CDC.

So, Should My Child Get Vaccinated?

The CDC, AAP, American Heart Association, and other major health organizations have taken the same stance: Everyone 12 and older should still get vaccinated against COVID-19. "The benefits of receiving the vaccine and preventing COVID outweigh the risk," says Dr. Abelowitz. 

Indeed, a June 23 statement co-signed by representatives from the CDC, American Academy of Pediatrics (AAP), American Academy of Family Physicians (AAFP), U.S. Department of Health and Human Services (HHS), and various other organizations said the following: "We strongly encourage everyone age 12 and older who are eligible to receive the vaccine under Emergency Use Authorization to get vaccinated, as the benefits of vaccination far outweigh any harm. 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."

Dr. Cohen agrees with the advice, adding that his 13-year-old son got vaccinated recently. "You look at COVID-19 itself, and there were 4 million cases in kids under 18," he said. Some of these kids have been hospitalized-and a few have died-from the coronavirus, and we still don't understand the long-term effects of the disease. 

It's also worth noting that myocarditis has been associated with the coronavirus. In fact, more people have been diagnosed with myocarditis after COVID-19 infection than after getting the Pfizer or Moderna vaccines. Myocarditis has also been seen with multisystem inflammatory syndrome in children (MIS-C)-a mysterious illness that affects about 1 in 1,000 kids infected with COVID-19, Paul Offit, M.D., a pediatrician and member of a Food and Drug Administration vaccine advisory committee, recently told NPR

Essentially, experts agree that contracting COVID-19 is more scary than the small chance your child could get myocarditis after receiving Pfizer or Moderna. Getting vaccinated is key to protecting your family and stopping the pandemic in its tracks.

The Bottom Line

Experts and organizations recommend that everyone 12 and older get vaccinated against COVID-19. That said, parents and children should look out for chest pain, shortness of breath, pounding heart, and other myocarditis symptoms after getting vaccinated. "Seek medical care if you think you or your child have any of these symptoms within a week after COVID-19 vaccination," says the CDC.