Myocarditis and COVID-19 Vaccines: The Latest News for Parents

Published on 
August 4, 2021


Two doctors share the facts on this rare reaction—and why vaccinating your child is still the safest choice.

By Katie Sweeney

Many parents have been concerned about reports of myocarditis—heart inflammation—in some young people who have received a COVID-19 vaccine.

This worry is understandable. But there’s also reassuring news: Heart inflammation after the vaccine is a very rare event. In addition, most cases have been mild, with patients recovering after a few days of treatment and rest.

Below, two Children’s Hospital Los Angeles physicians—Jennifer Su, MD, a pediatric cardiologist, and Michael Neely, MD, MSc, FCP, Chief of Infectious Diseases—explain what’s happened, the symptoms to look for and why vaccinating your child is still by far the safest choice.

What exactly has happened?

Health officials have observed an increased risk for heart inflammation in adolescents and young adults who have recently received either the Moderna or Pfizer-BioNTech vaccines. Most of these cases have been in teen boys and young men, ages 12 to 29. The Pfizer vaccine is authorized for use in patients as young as 12 years old; Moderna is authorized in patients 18 years and older.

Both myocarditis and pericarditis have been reported. Myocarditis is inflammation of the heart itself, and pericarditis is inflammation of the heart’s outer lining.

The risk of this reaction is very low—roughly 0.01%, or 1 in 10,000 cases. As of June 11, 296 million doses of mRNA vaccines (Pfizer and Moderna) had been administered in the U.S., with 52 million doses given to people ages 12 to 29.

How serious is it?

Heart inflammation is always taken seriously. But fortunately, most post-vaccine cases in young people have been short-lived, with patients getting better very quickly.

“It’s still early, but we don’t expect them to have any long-term consequences,” Dr. Su says. “In the majority of patients, their heart function has been completely normal. We monitor them very closely, but typically they are treated with nothing more than ibuprofen.”

In contrast, traditional cases of myocarditis in adolescents—typically caused by a viral infection—are often more severe. “This specific post-vaccine reaction generally falls in the milder spectrum of myocarditis,” she notes.

What are the symptoms?

Symptoms usually appear within a few days of receiving the Moderna or Pfizer vaccine, particularly after the second dose. The most common symptoms are:

  • Chest pain
  • Shortness of breath
  • Heart palpitations (fast heartbeat)

What if my child has this rare reaction?

“You should see your pediatrician, ideally within a day of the symptoms starting,” Dr. Neely says. “Be aware that other conditions besides myocarditis could cause these symptoms, too. It’s important to find out what’s happening.”

There are two very simple tests your doctor can do to quickly check if your child has myocarditis:

  • A blood test of troponin, a protein that’s released when heart inflammation is present
  • An electrocardiogram (EKG), which measures the heart’s rhythm and electrical activity

How is myocarditis treated?

Children with myocarditis are often hospitalized. Most patients with post-vaccine myocarditis have responded well to rest and ibuprofen and have gone home after a few days.

“We hospitalize patients to monitor them,” Dr. Su explains. “It’s usually out of an abundance of caution to make sure they’re safe and the inflammation completely resolves.”

As of late July, Children’s Hospital Los Angeles has treated eight cases of myocarditis in adolescent boys who had recently received a COVID-19 shot. It has not been determined if all those cases were caused by the vaccine.

Should my child still get a COVID-19 vaccine?

Yes, absolutely. This reaction is very rare and usually short-lived. The reality is there is no completely risk-free choice. Young people actually face a greater risk of myocarditis from COVID-19 itself. For example, a recent study of Big Ten college athletes who had previously had COVID-19 found that 2.3% of them showed signs of heart inflammation on cardiac MRIs.

“As a cardiologist, I am much less concerned about a very rare and usually self-resolving vaccine reaction than I am about COVID-19 and how it can impact our kids,” says Dr. Su. “The benefits of the vaccine far outweigh the risks.”

Dr. Neely adds that 3.8 billion doses of various COVID-19 vaccines have been given to people around the world so far. “With any therapy or medicine, there will always be rare events,” he says. “But these vaccines are among the safest and most effective ever developed. We have a lot of data now to show that.”

But aren’t kids and teens less likely to get severe illness from COVID-19?

Yes, but it’s not that simple. Adolescents and young adults who get COVID-19 can go on to develop long COVID—with persistent, sometimes debilitating symptoms. And contrary to popular belief, children and adolescents unfortunately can and do get hospitalized for COVID-19 (although not as often as adults)—and some have died.

A simple shot can prevent those outcomes. “For every million vaccines given to 12-to-24-year-olds, you’re preventing 30,000 cases of COVID infection, 2,000 hospitalizations and 20 deaths—all in that age range,” Dr. Neely explains. “You’re also preventing 10 cases of MIS-C, the serious post-COVID inflammatory condition in children.”

Vaccinating young people will also help slow community infection rates and the creation of new variants. That’s important given the rapid spread of the Delta variant—and the fact that school is starting soon.

“These vaccines are amazingly protective against severe disease, even for the Delta variant,”  Dr. Neely adds. “Right now, more than 90% of COVID-19 hospitalizations and more than 99% of deaths are people who have not been vaccinated.”

What if I still have questions or concerns?

Dr. Neely urges parents who feel unsure about the vaccine to talk with their pediatrician about their concerns.

A parent himself, he booked his 15-year-old son’s appointment to get the COVID-19 vaccine just two hours after his son became eligible.

“An hour later we were in the pharmacy with a needle in his arm,” Dr. Neely says. “I would do the same thing again today in a heartbeat. Because I know now that he’s protected, and he’s doing his part to protect his friends and neighbors, too.”


To find out what parents should know about the Delta variant, click here.

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