Vaccination may help prevent some cases of viral myocarditis by lowering the chance of infections such as influenza or COVID-19, which can sometimes inflame the heart muscle. It cannot prevent every virus linked to myocarditis, and no vaccine protects against myocarditis from all causes. The goal is to follow vaccines recommended for your age and health, while knowing that rare vaccine-related myocarditis has also been reported after some COVID-19 vaccines.
How can vaccination help prevent viral myocarditis?
Myocarditis is inflammation of the heart muscle. It can develop when certain infections affect the heart, although not every viral infection leads to this complication. Vaccination can help by protecting against specific viruses associated with myocarditis. When a vaccine reduces the chance of getting an infection, it may also reduce the opportunity for that infection to cause heart inflammation.
According to MedlinePlus, viruses associated with myocarditis include influenza, SARS-CoV-2, coxsackievirus, parvovirus, cytomegalovirus, and adenovirus. Vaccines are available for some infections, but there is no single vaccine that protects against every virus associated with myocarditis. The amount of protection also depends on the infection, the vaccine, and the person's individual circumstances.
Which vaccines may reduce the risk of virus-related heart inflammation?
Influenza vaccination
Influenza, commonly called the flu, can sometimes be associated with myocarditis. Seasonal influenza vaccination helps reduce the chance of getting the flu and can lower the risk of serious flu-related complications. By preventing some influenza infections, vaccination may reduce one potential route to viral myocarditis, although protection against the flu does not guarantee protection against heart inflammation.
The Centers for Disease Control and Prevention (CDC) explains that flu vaccination reduces the risk of influenza illness and its potentially serious complications. Vaccine effectiveness varies between seasons and individuals, and vaccinated people can still develop influenza. The main established purpose of the flu vaccine is to prevent influenza and reduce its complications, not to guarantee that myocarditis will never occur.
COVID-19 vaccination
COVID-19 can be associated with myocarditis and other heart-related complications. COVID-19 vaccination is intended to help protect against the infection and its consequences. Reducing the risk of COVID-19 may therefore help reduce exposure to one infection associated with heart inflammation, although vaccination cannot eliminate this risk completely.
A CDC analysis published in the Morbidity and Mortality Weekly Report found that recorded cardiac complications were more common following SARS-CoV-2 infection than after mRNA COVID-19 vaccination across the age and sex groups studied. These findings came from data collected between January 2021 and January 2022, so they describe that study period and should not be treated as a precise estimate of an individual's current risk.
Can vaccination prevent myocarditis caused by other viruses?
Not in every case. Several viruses linked to myocarditis do not have a routinely available vaccine that directly prevents those infections. For example, coxsackievirus, one of the enteroviruses associated with myocarditis, is not covered by a routine vaccine for general prevention. Vaccination against influenza or COVID-19 also does not protect someone from every other virus that may affect the heart.
Myocarditis can also develop for reasons unrelated to a viral infection, including certain medication reactions and immune-related conditions. This is why the most accurate answer is that vaccination may lower the risk of myocarditis associated with certain preventable infections, rather than prevent myocarditis as a whole.
Can a vaccine itself cause myocarditis?
Yes. Myocarditis has been reported as a rare adverse event after some COVID-19 vaccines, particularly mRNA vaccines. The risk pattern has varied by age, sex, vaccine dose, and vaccine type. This is important to distinguish from myocarditis associated with infection: both are possible, but they are not the same event.
According to the CDC's clinical guidance on myocarditis after COVID-19 vaccination, reported cases have occurred most often in adolescent and young adult males within seven days after the second dose of an mRNA vaccine. Cases have also occurred in females, in other age groups, and after other doses. The CDC notes that most patients with myocarditis following mRNA COVID-19 vaccination had resolution of symptoms by hospital discharge, although outcomes can differ.
The possibility of this rare adverse event does not mean that every vaccinated person faces the same risk or that vaccination should automatically be avoided. The balance of benefits and risks depends on the vaccine, the person's age and medical history, the infection being prevented, and current public-health guidance. Anyone who previously developed myocarditis or pericarditis after a COVID-19 vaccine should discuss any further doses with a healthcare professional before proceeding.
How can you reduce your risk of infection-related myocarditis?
There is no guaranteed way to prevent all cases of myocarditis, but sensible infection-prevention measures can reduce exposure to some viruses. Vaccination is one part of that approach. Other useful steps include washing your hands regularly, avoiding close contact with people who are acutely ill when practical, and following appropriate advice when respiratory infections are circulating.
Keep your vaccinations up to date according to the recommendations in your country and your healthcare professional's advice. The appropriate schedule may differ for children, adults, older people, pregnant individuals, and people with particular medical conditions. Your clinician can take your age, medical history, previous vaccine reactions, and current health into account when discussing suitable vaccines.
When should possible myocarditis symptoms be assessed?
Myocarditis can cause chest pain, shortness of breath, unusual tiredness, or a rapid or irregular heartbeat. These symptoms can have many causes, but new or unexplained chest pain or breathing difficulty requires urgent medical assessment. The American Heart Association advises seeking emergency medical help for unexplained chest pain or shortness of breath.
Symptoms that develop after a recent infection or vaccination should be assessed in context rather than attributed automatically to either one. Tell the healthcare professional about any recent illness, vaccination dates, medications, and relevant medical history. Seek urgent care for concerning heart or breathing symptoms rather than waiting to see whether they resolve on their own.
What is the main takeaway?
Vaccination can help prevent some infections that are associated with viral myocarditis, particularly influenza and COVID-19. This may reduce one pathway through which heart inflammation develops, but the protection is incomplete and does not extend to every virus or every cause of myocarditis. Although rare myocarditis has also been reported after some COVID-19 vaccines, the risks and benefits should be considered using current evidence and individual medical circumstances.