It’s been more than two years since the coronavirus pandemic began, and at least 259 million Americans have received at least one dose of a COVID-19 vaccine. The vast majority of people report mild side effects like injection site pain, body aches, and low-grade fever. But in April 2021, a small percentage of young people also began experiencing a rare symptom associated with the injection of the Pfizer or Moderna vaccines: an inflammation of the heart muscle called myocarditis.
Health care professionals began diagnosing patients under 30 with myocarditis at increased rates, says pediatrician Steven Abelowitz, M.D., the medical director of Coastal Kids pediatrics group in California. Most were males between the ages of 16 and 24, whose symptoms showed up three to five days after the second dose of these mRNA vaccines.
This is understandably worrying to parents, but there is good news: Developing myocarditis after getting vaccinated is rare; out of the more than 41 million people under 30 who’ve gotten the COVID vaccine, just 1,396 developed a confirmed case of myocarditis by March 2022, according to the CDC. The odds are vastly lower for kids under age 11. Plus, “most of the cases are short-lived and mild,” says Dr. Abelowitz. Most people (95%) who develop myocarditis after receiving a COVID-19 mRNA vaccine have only mild symptoms that go away within a few days.
In June 2021, the Food and Drug Administration (FDA) added a warning about myocarditis and pericarditis (inflammation of the sac-like layer surrounding the heart) to its “patient and provider fact sheets” for the Pfizer and Moderna vaccines. Both the FDA and CDC still advise that everyone age 6 months and over receive a COVID-19 vaccine. The potential consequences of contracting coronavirus (long-term health problems, hospitalization, death) far outweigh the risk of myocarditis after vaccination.
Here's what you need to know about the link between myocarditis and the 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 medication, autoimmune diseases, environmental toxins, and other factors.
Myocarditis has always been a relatively uncommon condition, even before it was potentially linked to the COVID-19 vaccines. “You probably see one or two cases per year in pediatric offices,” says Daniel Cohen, M.D., a pediatrician at Westmed Medical Group, in Purchase, New York. The condition mainly occurs between puberty and the early 30s, and generally affects males more than females.
Myocarditis usually isn't serious. Most individuals have no symptoms at all, and the condition can resolve on its own. If symptoms are present, they may include chest pain that worsens after exertion or lying down, rapid heartbeat, shortness of breath, fever, fatigue, lightheadedness, and fainting. In extreme cases, myocarditis leads to an abnormal heartbeat, heart failure, or (on rare occasions) death. If treatment is indicated, health professionals may prescribe anti-inflammatory medications or steroids.
Is There a Link Between Myocarditis and COVID-19 Vaccines?
Studies like this one in the Journal of the American Medical Association seem to suggest that, though they describe myocarditis as a “rare but serious adverse event.” The CDC says there is “a likely association”—and the increase shown in young males caused concern when it showed up in 2021 on VAERS, the Vaccine Adverse Event Reporting System overseen by the CDC and FDA.
By March 2022, more than 2,300 people under 30 reported symptoms of myocarditis or pericarditis after being vaccinated, according to VAERS, though just over half of those reports were confirmed. Millions had been vaccinated at that time. The American Heart Association (AHA) acknowledges that myocarditis is occurring among the young in higher numbers compared to other groups, yet it says symptoms are usually mild and recovery quick.
In December 2021, the AHA journal Circulation published a review of post-vaccine myocarditis at 26 pediatric medical centers in the U.S. and Canada. Among the millions of people age 12 to 20 who'd gotten the vaccine in their communities before July 4, 2021, just 136 were evaluated for suspected myocarditis afterward, and most ended up in the hospital for less than three days. None died.
"Most cases of suspected COVID-19 vaccine myocarditis occurring in persons under 21 years have a mild clinical course with rapid resolution of symptoms," the study authors wrote.
So, Should My Child Get Vaccinated?
The CDC, AHA, American Association of Pediatrics, and other major health organizations have all taken the same stance: Everyone age 6 months and older should still get vaccinated against COVID-19. “The benefits of receiving the vaccine and preventing COVID outweigh the risk,” agrees Dr. Abelowitz.
In fact, your kids are far more likely to get myocarditis from COVID-19 than from the vaccines that fight it. Dr. Cohen also supports getting them vaccinated, adding that his teen son got the shot recently. “Look at COVID-19 itself,” he urges, pointing out the number of kids that have been hospitalized—or died—from the coronavirus. And we still don’t understand the long-term effects of the disease.”
The numbers seem smaller when you break them down. With the Pfizer vaccine, for example, just eight children under 11 developed myocarditis between May and December 2021 (out of 8.7 million doses); so did just 265 kids age 12 to 15 (out of nearly 19 million doses). The same held for boosters, as just 13 individuals age 16 to 24 reported myocarditis symptoms (of 1 million getting boosted).
It’s always hard when your kids are involved, but there’s another good reason to get them vaccinated. Myocarditis is a symptom of multisystem inflammatory syndrome in children (MIS-C)—the potentially fatal illness that shows up about two to six weeks after kids get COVID-19. MIS-C has so far affected nearly 8,000 children (median age: 9) as of March 28, 2022; of those, 66 have died. Pfizer’s vaccine was shown in a recent study to reduce the likelihood of MIS-C by 91% among those 12 to 18.
Experts agree that contracting COVID-19 is scarier than the odds your child could get myocarditis from Pfizer or Moderna. Getting vaccinated protects your family and helps stop the pandemic in its tracks.
The Bottom Line
The top health care organizations recommend that children age 5 and older get vaccinated against COVID-19. That being said, parents should look out for chest pain, shortness of breath, pounding heart, and other myocarditis symptoms in their kids post-vaccine. "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.
