Myocarditis is an inflammatory disease of the heart muscle, whilst pericarditis is an inflammatory disease of the lining of the heart muscle. They are rare conditions, most commonly associated with viral infections (including SARS-CoV-2) but can also be triggered by other factors such as medications and autoimmune conditions.

Globally, an increased number of cases above an expected population rate of myocarditis and pericarditis have been reported in individuals who have received mRNA COVID-19 vaccines (eg. Comirnaty (Pfizer) and Spikevax (Moderna)).

Myocarditis

  • How is myocarditis triggered following mRNA vaccination?

    The exact mechanism behind cardiac inflammation temporally associated with a COVID-19 mRNA vaccine is currently being investigated. Clinical causes from international surveillance data suggest an immune-mediated or hypersensitivity trigger.

  • Who is at risk of myocarditis?

    Myocarditis from any cause, occurs more commonly in males than females. It is also more likely to affect younger adults.

    Reported rates of myocarditis occurring following administration of an mRNA COVID-19 vaccine vary; however, they are above expected background rates. The peak risk group is young adult males aged 16-17 years, with a smaller increased risk for males aged between 12-24 years.

    International vaccine safety surveillance data currently suggests that it is more commonly associated with administration of a second dose of a COVID-19 mRNA vaccine.

  • Pre-existing cardiac conditions and mRNA vaccination

    Individuals with the following cardiac conditions can safely receive COVID-19 mRNA vaccines without the need for additional monitoring or precautions:

    • coronary artery disease
    • myocardial infarction
    • stable heart failure
    • arrhythmias
    • rheumatic fever
    • rheumatic heart disease
    • kawasaki disease
    • most congenital heart disease
    • those with implanted cardiac devices
    • congenital heart disease
    • cardiac transplant
    • cardiomyopathy.

    Those with a history of the following conditions can also receive COVID-19 mRNA vaccines; however should consult their treating specialist to determine the appropriate timing for vaccination:

    • recent (within 3 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis)
    • acute rheumatic fever or acute rheumatic heart disease
    • acute decompensated heart failure.

    Patients with ongoing cardiac inflammation should have vaccination deferred. Individuals aged 60 years or over can receive an alternate COVID-19 vaccine brand (eg. Vaxzevria (AstraZeneca)).

  • What are the symptoms of myocarditis?

    Myocarditis presents similarly to pericarditis, with a range of symptoms including:

    • chest pain, pressure or discomfort
    • pain with breathing (pleuritic chest pain)
    • shortness of breath
    • palpitations
    • syncope (faint)
    • other non-specific symptoms such as fatigue, dizziness, abdominal pain

    In individuals who have received COVID-19 mRNA vaccines, symptoms of myocarditis related to COVID-19 mRNA have most commonly been reported within 2-7 days of second dose vaccination.

  • How is myocarditis after COVID-19 vaccination diagnosed and investigated?

    If there is suspicion of myocarditis, particularly in the first week following vaccination, timely medical review is important. Those who appear unwell should be referred to an emergency department for examination and the following primary investigations:

    • blood tests for cardiac biomarkers, such as troponin
    • electrocardiogram (ECG).

    Other tests should be considered if the patient is unwell or the tests above are abnormal:

    • chest X-ray (CXR)
    • other tests related to investigating differential diagnoses such as inflammatory markers (C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
    • bedside or formal ultrasound/echo
    • cardiac MRI

    Consistent findings of myocarditis may include elevated troponin, ECG changes (ST or T-wave abnormalities, premature atrial or ventricular complexes) as well as abnormal echocardiogram or cardiac MRI.

    Individuals who are investigated for myocarditis following mRNA vaccination should avoid high-intensity exercise until symptoms have resolved is recommended.

    Cardiologist advice and followup is strongly recommended.

  • How is myocarditis after COVID-19 vaccination treated?

    Current data shows that most cases of myocarditis following COVID-19 mRNA vaccination have mild symptoms and recover well. Information on long term sequelae is not yet available.

    Treatment of these conditions is managed by a cardiologist and include in-patient supportive therapies. In the rare severe or complicated cases, specific management for arrythmias, decreased cardiac function or congestive cardiac failure with pharmacological agents such as ACE-inhibitors and beta-blockers or mechanical support may be necessary.

  • I have specific questions around my risk of myocarditis following COVID-19 mRNA vaccines. Help!

    Please refer to our FAQs on COVID-19 mRNA vaccines for further information. This includes answers on:

    • impact of dose intervals between 1st and 2nd dose of mRNA vaccine
    • risk of developing myocarditis from COVID-19 disease vs the vaccine
    • exercise after COVID-19 mRNA vaccines
    • impacts of medications and drugs such as clozapine, stimulants, amphetamines on developing myocarditis.
  • Implications for future vaccine doses

    For individuals where the cause of inflammation is attributed to COVID-19 mRNA vaccination a report to SAEFVIC is indicated and a referral to a cardiologist and/or specialist immunisation service (eg. VicSIS) is recommended.

    Please refer to the suggested algorithm below with reference to implications for future COVID-19 vaccine doses after myocarditis.

    *Brighton Level refers to Brighton Collaboration criteria for classifying myocarditis
    PDF version of the above diagram available here.

    At this time, ATAGI recommends that further doses of COVID-19 mRNA vaccines are deferred and the individual referred to a specialist immunisation clinic. Ongoing data and evaluation of myocarditis after third or booster doses of COVID-19 vaccines is underway.

  • What is the risk/benefit ratio for vaccination for the young adult age group?

    It is important to discuss your individual circumstances with a health care provider in order to make an informed decision.

    The level of COVID-19 community transmission in Australia can change quickly. Factors to consider include age, potential for exposure to the virus (including in the workplace), high rates of global transmission, the emergence of new variants of the virus, as well as the potential for future changes to Australia’s border controls.

    Whilst COVID-19 infection can sometimes result in myocarditis, its incidence following COVID-19 vaccination is comparatively extremely rare. Most individuals diagnosed with myocarditis following COVID-19 vaccination have responded well to treatment.

Pericarditis

  • How is pericarditis triggered following mRNA vaccination?

    The exact mechanism behind cardiac sac inflammation temporally associated with a COVID-19 mRNA vaccine is currently being investigated. Clinical causes from international surveillance data suggest an immune-mediated or hypersensitivity trigger.

  • Who is at risk of pericarditis?

    Pericarditis from any cause, occurs more commonly in males than females. It is also more likely to affect younger adults.

    Reported rates of pericarditis occurring following administration of an mRNA COVID-19 vaccine vary; however, they are above expected background population rates.

    International and local data suggest that pericarditis following mRNA COVID-19 vaccines is more common in the 25-49 year old age group for both males and females.

  • Pre-existing cardiac conditions and mRNA vaccination

    Individuals with the following cardiac conditions can safely receive COVID-19 mRNA vaccines without the need for additional monitoring or precautions:

    • coronary artery disease
    • myocardial infarction
    • stable heart failure
    • arrhythmias
    • rheumatic fever
    • rheumatic heart disease
    • kawasaki disease
    • most congenital heart disease
    • those with implanted cardiac devices
    • congenital heart disease
    • cardiac transplant
    • cardiomyopathy.

    Those with a history of the following conditions can also receive COVID-19 mRNA vaccines; however should consult their treating specialist to determine the appropriate timing for vaccination:

    • recent (within 3 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis)
    • acute rheumatic fever or acute rheumatic heart disease
    • acute decompensated heart failure.

    Patients with ongoing cardiac inflammation should have vaccination deferred. Individuals aged 60 years or over can receive an alternate COVID-19 vaccine brand (eg. Vaxzevria (AstraZeneca)).

  • What are the symptoms of pericarditis?

    Pericarditis presents similarly to myocarditis, with a range of symptoms including:

    • chest pain, pressure or discomfort
    • pain with breathing (pleuritic chest pain)
    • shortness of breath
    • palpitations
    • syncope (faint)
    • other non-specific symptoms such as fatigue, dizziness, abdominal pain.
  • How is pericarditis after COVID-19 vaccination diagnosed and investigated?

    If there is suspicion of either of these conditions, particularly in the first 2-3 weeks following vaccination, timely medical review is important. Those who appear unwell should be referred to an emergency department for the following investigations:

    • blood tests for cardiac biomarkers, such as troponin
    • electrocardiogram (ECG)

    Other tests should be considered if the patient unwell or the tests above are abnormal:

    • chest X-ray (CXR)
    • other tests related to investigating differential diagnoses such as inflammatory markers (C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)).

    Consistent findings of pericarditis include a pericardial rub on auscultation, widespread ST-elevation or PR depression on ECG, as well as pericardial effusion on imaging.

    Individuals who are investigated for pericarditis following mRNA vaccination should avoid high-intensity exercise until symptoms have resolved is recommended. Those experiencing ongoing symptoms should return for review in 1-2 days time. Cardiologist advice is recommended if clinical suspicion is high, regardless of normal investigations.

  • How is pericarditis after COVID-19 vaccination treated?

    Current data shows that most cases of pericarditis following COVID-19 mRNA vaccination have mild symptoms and recover well. Information on long term sequelae is not yet available.

    Treatment of these conditions is managed by a cardiologist and include in-patient supportive therapies, often with anti-inflammatory medications or colchicine. In the rare severe or complicated cases, specific management for arrythmias, decreased cardiac function or congestive cardiac failure with pharmacological agents such as ACE-inhibitors and beta-blockers or mechanical support may be necessary.

  • Implications for future vaccine doses

    For individuals where the cause of inflammation is attributed to COVID-19 mRNA vaccination a report to SAEFVIC is indicated and a referral to a cardiologist and/or specialist immunisation service (eg. VicSIS) is recommended.

    Please refer to the suggested algorithm below with reference to implications for future COVID-19 vaccine doses after pericarditis.

    *Brighton Level refers to Brighton Collaboration criteria for classifying pericarditis
    Access a pdf version of this guide here.

    In particular, the groups which are at lower risk (green in algorithm), could proceed with further doses of COVID-19 vaccination as per above suggested instructions.

    Ongoing data and evaluation of pericarditis after third or booster doses of COVID-19 vaccines is underway.

  • What is the risk/benefit ratio for vaccination for the young adult age group?

    It is important to discuss your individual circumstances with a health care provider in order to make an informed decision.

    The level of COVID-19 community transmission in Australia can change quickly. Factors to consider include age, potential for exposure to the virus (including in the workplace), high rates of global transmission, the emergence of new variants of the virus, as well as the potential for future changes to Australia’s border controls.

    Whilst COVID-19 infection can sometimes result in pericarditis, its incidence following COVID-19 vaccination is comparatively extremely rare. Most individuals diagnosed with pericarditis following COVID-19 vaccination have responded well to treatment.

Authors: Rachael McGuire (MVEC Education Nurse Coordinator), Francesca Machingaifa (MVEC Education Nurse Coordinator), Daryl Cheng (MVEC Medical Lead) and Nigel Crawford (Director SAEFVIC, Murdoch Children’s Research Institute)

Reviewed by: Daryl Cheng (MVEC Medical Lead)

Date: November 11, 2021

Materials in this section are updated as new information and vaccines become available. The Melbourne Vaccine Education Centre (MVEC) staff regularly reviews materials for accuracy.

You should not consider the information in this site to be specific, professional medical advice for your personal health or for your family’s personal health. For medical concerns, including decisions about vaccinations, medications and other treatments, you should always consult a healthcare professional.