What Is the Risk of Developing Myocarditis or Pericarditis From a COVID Vaccine?

When the first COVID-19 vaccines were introduced, many people questioned their safety. Even though mRNA vaccines were new, the technology behind them was based on years of scientific research that began in the 1960s.  

Although the mRNA vaccines are generally very safe, they’ve been linked to rare cases of heart complications known as myocarditis and pericarditis. These conditions cause inflammation of the heart. People who develop these conditions usually get better within a few days. However, some people still have avoided getting vaccinated out of fear of these complications. 

We’ll go through everything you need to know about myocarditis and the COVID vaccine, so you can make the best decision for you. 

What is myocarditis and pericarditis?

Myocarditis is a condition in which the heart muscle (myocardium) becomes inflamed. When you have myocarditis, your heart may not be able to pump blood as well as a healthy heart muscle. Myocarditis is different from a heart attack. That’s because heart attacks are usually caused by blocked arteries. But both conditions can cause the heart to become weak.  

Causes of myocarditis include: 

• Common viruses, including the virus that causes the flu, SARS-CoV-2, and some viruses that infect the gastrointestinal (GI) tract 

• Cocaine and other drugs 

• Excessive alcohol

• Autoimmune diseases

• Some psychiatric medications

• Some cancer treatments

• Some vaccines, including the COVID-19 shots

Pericarditis is a condition in which the lining of the heart (pericardium) becomes inflamed. In some cases, the inflammation can lead to fluid buildup around the heart. If there’s a lot of fluid, it can compress the heart. This will make it hard for the heart to effectively pump blood.

Like myocarditis, pericarditis can be caused by viral infections. Certain medications, some vaccines, and some autoimmune conditions can also cause pericarditis. So can things like kidney failure, trauma, and radiation therapy to the chest. Sometimes pericarditis and myocarditis happen at the same time. 

How common is myocarditis after COVID vaccination?

Myocarditis is an uncommon side effect of the mRNA COVID-19 vaccines. The chance of getting myocarditis after the vaccine is estimated to be about 2 people for every 100,000. Putting that into perspective, your lifetime chances of getting hit by lightning are 7 in 100,000. So your risk is very low.

Men and boys between the ages of 16 and 29 are more likely than others to get myocarditis from the vaccine. When the vaccine first came out, two doses were required. And the risk was higher after the second dose of the original vaccine. With the Pfizer vaccine, the risk for myocarditis was up to 7 per 100,000 males ages 16 through 29. With the Moderna vaccine, the risk was up to 28 per 100,000 young men vaccinated. That’s still a small number, but higher than what’s seen in other groups.

The good news is that 95% of the time the symptoms get better within days. But about 1% of people with this very uncommon complication may die from it.

It’s important to remember that the virus itself can cause heart complications. Myocarditis is seven times more common with COVID-19 compared with the vaccine. The risk with the virus might also be higher in younger men compared with other groups. 

“COVID vaccination-related myocarditis is possible but extremely rare,” said Dr. David Rawitscher, the regional medical director of advanced heart failure at Baylor Scott & White The Heart Hospital. “It is much more common and dangerous to get myocarditis from a COVID infection.”

Why does the COVID vaccine cause myocarditis?

Research into the cause of the myocarditis reaction suggests that it’s due to a strong immune response to the vaccine. Younger men may have more reactive immune systems. That may be why they’re more likely to get myocarditis and pericarditis. But we still don’t know exactly why this group is at higher risk.

The reaction doesn’t appear to be an allergy or an autoimmune reaction. 

What are symptoms of myocarditis?

The symptoms of myocarditis may include:

• Chest pain

• Shortness of breath

• Palpitations or a racing heartbeat

• Fevers that last for several days

• Abnormal swelling of your feet and legs

• Lightheadedness or dizziness

The symptoms of pericarditis may include:

• Stabbing chest or back pain, often worse with a deep breath

• Fever

• Shortness of breath

• Palpitations

• Fatigue

If you experience these symptoms, it’s best to go to your nearest emergency room as quickly as possible. This way, a healthcare provider can evaluate your heart function sooner rather than later. And also look for other heart conditions that could be causing your symptoms.

Keep in mind that it’s common to experience mild to moderate side effects after your vaccination. The most common symptoms are: 

• Pain at the injection site

• Fatigue

• Body aches

• Chills

• Nausea

• Headache 

These symptoms usually resolve on their own in 1 to 2 days.

How is myocarditis treated?

If you receive a diagnosis of  myocarditis or pericarditis, you’d usually receive treatment from a cardiologist. Along with blood testing, you’d get an echocardiogram. This is an ultrasound of your heart that can measure heart function. You might also get a cardiac MRI test. These tests will look for heart enlargement, weakening, excess fluid, and inflammation.

Treatment typically includes anti-inflammatory medications. This might mean prescription-strength doses of NSAIDs like ibuprofen. You may also receive a medication called colchicine. This medication is often used to treat gout, but it’s standard care for pericarditis as well. Sometimes steroids like prednisone are needed. In more serious cases of weak heart function, you may receive additional heart medications.

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Written by:

Sarah A. Samaan, MD

Sarah Samaan, MD, FACC, FACP, FASE is a board-certified cardiologist who practiced clinical cardiology for nearly 30 years. She is a member of the American College of Cardiology and the American College of Physicians, among others.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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