Myocarditis and Covid-19 vaccines
We look at the link between myocarditis and Covid-19 vaccines.
Updated 11 April 2024
What's on this page
Do Covid-19 vaccines cause myocarditis and pericarditis?
There is a link between mRNA Covid-19 vaccines and an increased risk of myocarditis and pericarditis.
Myocarditis is inflammation of the heart muscle and pericarditis is inflammation of the lining around the heart.
While reports of myocarditis following any Covid-19 vaccine are rare, cases are more common in young males under the age of 25, according to the UK’s Green Book on vaccines.
The risk appears to be higher after a second dose of the vaccine, compared with the first dose or booster doses.
As of Spring 2024, only those aged 75 and over, residents in care homes and those with a weakened immune system are being offered a booster dose.
How rare are these side effects?
The risk of myocarditis and pericarditis after a Covid-19 vaccine is very low.
Patient leaflets for each Covid-19 vaccine list how frequently people experience myocarditis or pericarditis after being vaccinated as:
All three of these Covid-19 vaccines are mRNA vaccines designed to target the Omicron strain.
The AstraZeneca Covid-19 vaccine, which is a non-mRNA vaccine, is not currently being offered in the UK.
Can Covid-19 cause myocarditis and pericarditis?
Research shows that Covid-19 itself is much more likely to cause myocarditis than the vaccine.
People who are vaccinated against Covid-19 also have a much lower risk of getting other serious heart complications caused by the virus, including heart attack and stroke.
That is why the Medicines and Healthcare products Regulatory Agency (MHRA) says the benefits of having the Covid-19 vaccine far outweigh the risks of not getting it for most people.
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What is myocarditis?
Myocarditis is inflammation of the heart muscle.
There are many different causes of myocarditis, so not all cases that happen after vaccination are because of the vaccine.
For instance, myocarditis commonly happens in response to viruses, such as flu or Covid-19. It can also happen in response to bacterial infections, such as a sore throat or chest infection.
Myocarditis can be mild or serious. Most people who get acute myocarditis make a good recovery and do not have long-term problems.
But in serious cases it can lead to scarring of the heart tissue, which can be seen on a cardiac MRI scan.
In a small number of cases this scarring may cause a life-threatening heart rhythm disturbance later in life, and those affected are likely to be offered long-term follow-up and monitoring.
Myocarditis may also make it more difficult for your heart to pump blood around your body properly (heart failure).
What is pericarditis?
Pericarditis is inflammation of the lining around the heart, whereas myocarditis is inflammation of the heart muscle.
Pericarditis and myocarditis often happen together and can have similar effects.
What are the symptoms of myocarditis?
Symptoms of myocarditis linked to the Covid-19 vaccine generally appear within a week of vaccination. You should seek medical help if you get any of these symptoms:
- chest pain or discomfort, or a feeling of tightness in the chest
- shortness of breath, either at rest or when active, or in certain positions, such as lying down
- palpitations (like your heart is fluttering, racing, or pounding).
They may not mean you have myocarditis, but they are signs you should get medical help, whether you have recently been vaccinated or not.
What research is happening?
Since the beginning of the Covid-19 pandemic, British Heart Foundation has been committed to supporting research into the direct and indirect impacts of Covid-19 on cardiovascular health.
This has included research into the links between Covid-19 and Covid-19 vaccines and myocarditis and pericarditis.
Through BHF’s partnership with the National Institute for Health and Care Research (NIHR), we have supported seven key Covid-19 research projects.
Two of these projects (CVD-COVID-UK / COVID-IMPACT) are led by researchers at the BHF Data Science Centre, who are trying to understand the relationship between Covid-19 and cardiovascular diseases such as heart attack, heart failure, stroke, and blood clots in the lungs.
They include research looking at the effects of Covid-19 infection and vaccination on the risk of myocarditis and pericarditis.
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