These COVID-19 vaccine FAQs have been designed to address common queries relating to mRNA vaccines.

Please also see our other COVID-19 FAQs for more information on other COVID-19 related topics:

For ease of reference, information has been categorised as per the below themes:

This page will be updated on a regular basis as further information becomes available regarding COVID-19 vaccines.

For questions that have not been addressed on this page or our dedicated COVID-19 resource page, please email info.mvec@mcri.edu.au for further clarification.

General

  • How do mRNA vaccines work?

    mRNA and DNA vaccines are genetic vaccines. They allow the genetic material of viral proteins (small parts of a pathogen) to be recreated by human cells as an antigen. Once the antigen has been identified by the immune system, antibodies and memory cells are produced to provide protection against future infection.

    Although DNA and mRNA vaccines had not been licensed prior to the COVID-19 pandemic, they were already under development for other viruses, such as influenza.

  • Can mRNA vaccines alter my DNA?

    No. It is not possible to integrate vaccine mRNA into an individual’s own DNA. mRNA from vaccines are unable to enter the nucleus of a human cell (where a person’s genetic material is stored). It is also not possible for vaccine mRNA to revert to DNA. In addition, mRNA from COVID-19 vaccines only provide the code for part of the pathogen (eg. the spike protein on the outer surface of a SARS-CoV-2 virus) and not the whole pathogen.

    For more information refer to CHOP: Can mRNA vaccines alter a persons DNA?

  • Do COVID-19 vaccines cause viral shedding?

    None of the COVID-19 vaccines used within Australia contain live virus and therefore people who are vaccinated cannot shed or transmit the virus to other people.

    COVID-19 disease itself is highly infectious and can be transmitted via respiratory secretions.

  • What ingredients are NOT in mRNA COVID-19 vaccines?

    The following products are NOT ingredients in mRNA COVID-19 vaccines:

    • Animal products
    • Antibiotics
    • Blood products
    • DNA
    • Egg proteins
    • Foetal material
    • Gluten
    • Microchips
    • Pork products
    • Thiomersal
    • Soy
    • Latex
    • Aluminium

    Further information can be found in the vaccine product information:

Pre-existing conditions

  • Can people with pre-exisiting cardiac (heart) conditions receive mRNA COVID-19 vaccines?

    The overwhelming majority of pre-existing cardiac conditions are not regarded as contraindications to vaccination with COVID-19 mRNA vaccines. 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 6 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis)
    • acute rheumatic fever or acute rheumatic heart disease
    • acute decompensated heart failure.
  • What are the vaccine recommendations for people who have previously been diagnosed with myocarditis or pericarditis?

    Individuals with recent (within 6 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis) can still receive COVID-19 vaccines however should consult their treating specialist before doing so to determine the best time to be immunised.

    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 is recommended. At this time, ATAGI recommends that further doses of COVID-19 mRNA vaccines are deferred and the individual referred to a specialist immunisation clinic.

    For more information please refer to COVID-19 vaccination- Guidance on Myocarditis and Pericarditis after mRNA COVID-19 vaccines.

  • I have had a recent blood transfusion, can I have a COVID-19 vaccine?

    Vaccine recommendations following blood transfusion generally apply to live-attenuated vaccines, such as MMR (measles-mumps-rubella) or varicella vaccines. There are currently no live-attenuated COVID-19 vaccines planned for use in Australia. Comirnaty (Pfizer) and Spikevax (Moderna) are mRNA vaccines and Vaxzevria (AstraZeneca) is a non-replicating viral vector vaccine.

    For more information please refer to the CDC: COVID-19 Vaccine FAQs for Healthcare Professionals and MVEC: Live-attenuated vaccines and immunoglobulins or blood products.

  • When should people who have previously tested positive for COVID-19 disease be vaccinated?

    Evidence suggests that infection with COVID-19 will provide protection against reinfection for up to 6 months. There is no minimum interval recommendation between infection and vaccination however waiting approximately 6 months is considered appropriate. In patients who have fully recovered from acute illness, earlier vaccination may be considered noting there have been no safety concerns identified in immunising people with a history of past infection. Individuals suffering prolonged symptoms (longer than 6 months) can consider vaccination on a case-by-case basis following discussion with their GP.

    Side effects following vaccination for individuals with a history of past COVID-19 infection occur at either similar or decreased rates compared with recipients who have not been infected with COVID-19 disease.

    Please refer to COVID-19 vaccination – ATAGI clinical guidance on COVID-19 vaccine in Australia in 2021 or Victorian COVID-19 vaccination guidelines for more information.

  • Can people with a history of breast cancer receive COVID-19 vaccines?

    Yes. COVID-19 vaccination is recommended for all immunosuppressed people (including those undergoing treatment for cancers) due to an increased risk of developing severe disease if infected with SARS-CoV-2. It is anticipated that the immune response to vaccination may be reduced in this patient group depending on the level of immune suppression.

    Lymphadenopathy has been reported as a side effect following vaccination. Given that changes in size and consistency of lymph nodes can also indicate a spread of breast cancer, the Society of Breast Imaging (SBI) has recommended breast screening take place either prior to COVID-19 vaccination or 4-6 weeks following the second dose of COVID-19 vaccines to avoid anxiety and unnecessary examination and diagnostic testing.

    For more information please refer to Health.com – Swollen Lymph Nodes Under Armpit After COVID-19 Vaccine May Mimic Breast Cancer Symptoms—Here’s What to Know and Peter Mac COVID:19 vaccination: frequently asked questions.

  • Are anthracycline therapies considered a contraindication to mRNA COVI-19 vaccines due to the association with myocarditis/pericarditis?

    Children who have been treated with chemotherapeutic agents including anthracyclines as part of their cancer therapy are not considered as higher risk of side effects from vaccination (including the development of myocarditis/pericarditis. Parents/guardians should speak to their treating team regarding COVID-19 vaccination based on current recommendations.

    For further information refer to COVID-19 Vaccination Guidance for children 12 years and older undergoing cancer treatment and children with non-cancerous blood disorders.

  • My patient has a history of Guillain-Barre Syndrome (GBS), is it safe to administer COVID-19 vaccines?

    Individuals who have previously been diagnosed with GBS can receive COVID-19 vaccines. Specialist advice from a treating neurologist or immunisation specialist may be considered to discuss the benefits and risks of vaccination.

    For more information please refer to MVEC: Guillain-Barre Syndrome and CDC: Vaccine Considerations for People with Underlying Medical Conditions.

  • Are there any concerns regarding COVID-19 vaccines and Bell's Palsy?

    People who have previously been diagnosed with Bell’s Palsy can receive COVID-19 vaccines. Cases of Bell’s Palsy following immunisation have been identified in participants in mRNA COVID-19 vaccine candidate clinical trials. However, as the rate of occurrence was not above the background rate expected in the general population, they are not considered to be caused by vaccination.

    For more information refer to CDC: Vaccine Considerations for People with Underlying Medical Conditions.

  • Is it safe for people with Multiple Sclerosis to be immunised against COVID-19 disease?

    Yes. Whilst there is minimal data on the safety and efficacy of COVID-19 vaccination in people with MS, there are no theoretical concerns relating to administration in this patient group.

    For more information please refer to MS Australia: COVID-19 vaccination guidance for people with MS and MVEC: COVID-19 vaccines in people with immunocompromise.

  • Can patients who are taking monoamine oxidase inhibitors (MAOI's) be safely immunised with COVID-19 vaccines given that they should generally avoid adrenaline? What would be the appropriate treatment if they experienced anaphylaxis?

    Yes, COVID-19 vaccines should be offered to this patient group. True vaccine allergy, or anaphylaxis, is an extremely rare adverse event following immunisation occurring in less than 1 case per million doses administered.

    Patients who take MAOI’s have a theoretical increased risk of developing hypertensive crisis if administered adrenaline (or other specific medications/foods) due to a potential for drug interaction. In the setting of anaphylaxis, resuscitation with adrenaline remains the most appropriate treatment regardless of medical history. The benefits of treating anaphylaxis effectively far outweighs any potential risk of hypertensive crisis.

    Ensuring the diagnosis of anaphylaxis is accurate is an important step to avoid unnecessary administration of adrenaline when not clinically indicated.

    For more information refer to Australian Immunisation Handbook: Adverse events following immunisation or MVEC: COVID-19 vaccines and allergy.

  • Can COVID-19 vaccines be given to immunosuppressed individuals?

    It is recommended that all individuals aged 12 and over with immunosuppression receive COVID-19 vaccines. Having a lowered immune system increases the likelihood of developing severe disease and complications if infected with SARS-CoV-2. Due to the restricted eligibility criteria in early vaccine clinical trials, there is currently minimal data on the safety and efficacy of COVID-19 vaccination in this group. In principle, there are no theoretical safety risks and no vaccine safety signals have been identified for people with immunocompromise to date.

    People with immunocompromise receiving COVID-19 vaccination should be counselled about the possibility of reduced efficacy and the need to continue other preventative measures such as social distancing, mask wearing and hand hygiene. Household contacts should be encouraged to receive the COVID-19 vaccine when it is offered because vaccination has also been shown to reduce transmission.

    Please refer to ATAGI – Provider guide to COVID-19 vaccination of people with immunocompromise for more information.

  • My patient has a history of allergy to Polyethylene Glycol (PEG), can I administer a COVID-19 vaccine to them?

    PEG is an ingredient contained in Comirnaty (Pfizer) and Spikevax (Moderna). It is also a commonly used ingredient of other medications, hand sanitisers, cosmetics, bathroom products and colonoscopy preparation products, routinely used within Australia. Whilst it is uncertain whether PEG contained in mRNA vaccines may trigger anaphylaxis, additional precautions are required.

    If your patient has a history of confirmed or suspected allergy to PEG it is recommended that they are referred to an immunology/allergy/vaccination specialist for advice regarding the safety of administering an mRNA COVID-19 vaccine.

    NB: Vaccination with the Comirnaty or Spikevax is contraindicated in people with documented anaphylaxis to PEG.

    To read more refer to COVID-19 vaccination – ATAGI clinical guidance on COVID-19 Vaccine in Australia in 2021.

Myocarditis/pericarditis

  • Can people with pre-exisiting cardiac (heart) conditions receive mRNA COVID-19 vaccines?

    The overwhelming majority of pre-existing cardiac conditions are not regarded as contraindications to vaccination with COVID-19 mRNA vaccines. 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 6 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis)
    • acute rheumatic fever or acute rheumatic heart disease
    • acute decompensated heart failure.
  • What are the vaccine recommendations for people who have previously been diagnosed with myocarditis or pericarditis?

    Individuals with recent (within 6 months) or current inflammatory cardiac conditions (including myocarditis, pericarditis and endocarditis) can still receive COVID-19 vaccines however should consult their treating specialist before doing so to determine the best time to be immunised.

    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 is recommended. At this time, ATAGI recommends that further doses of COVID-19 mRNA vaccines are deferred and the individual referred to a specialist immunisation clinic.

    For more information please refer to COVID-19 vaccination- Guidance on Myocarditis and Pericarditis after mRNA COVID-19 vaccines.

  • I am taking certain medications that have myocarditis listed as an uncommon side effect. Am I at greater risk or developing myocarditis/pericarditis after mRNA vaccination?

    Some patients will be taking prescribed medications that have myocarditis listed as an uncommon side effect (e.g. antipsychotic drugs and biological chemotherapeutic agents). Treatment with these medications does not constitute a contraindication to vaccination with an mRNA COVID-19 vaccine.

    Vaccination remains the greatest protection an individual can have against severe COVID-19 disease, and mRNA vaccines remain the preferred option in Australia for those under the age of 60.

  • Are there impacts of other substances on the development of myocarditis/pericarditis after mRNA vaccines?

    If clinicians are aware that any individual uses recreational stimulants (particularly amphetamines), they should discourage patients from the use of these stimulants, especially in the week following their mRNA COVID-19 vaccine.

  • Should vaccinees not exercise after receiving their mRNA vaccine? Does this reduce the chance of myocarditis/pericarditis?

    Exercise is not thought to exacerbate the risk of myocarditis/pericarditis following mRNA COVID-19 vaccines.  It is not necessary to advise all individuals receiving an mRNA COVID-19 vaccine to avoid exercise following vaccination.

    However, if patients develop myocarditis/pericarditis post mRNA COVID-19 vaccination there is a concern that exercise may be pro-arrhythmic (eg. will exacerbate) the condition.

    As part of routine pre-vaccination education and consent, all vaccinees should be informed of the symptoms of myocarditis and pericarditis, and advised that should they develop symptoms, they must avoid exercise and they must seek medical attention.

    For more information please refer to COVID-19 vaccination- Guidance on myocarditis and pericarditis after mRNA COVID-19 vaccines

  • How should I investigate/manage chest pain that presents after mRNA vaccination? Are there suggested guidelines?

    There are a number of clinical guidelines that have been developed to aid clinicians in investigating potential myocarditis/pericarditis following mRNA vaccination.

    As chest pain may be due to a variety of causes, ranging from minor to life-threatening, it is important to encourage all patients to present promptly for medical evaluation of any episode of chest pain associated with COVID-19 mRNA vaccines.

  • How common is myocarditis/pericarditis related to COVID-19 mRNA vaccine?

    Current data on this adverse event following immunisation (AEFI) from Victoria, Australia is available here.

    Overseas data from the USA for specific age groups estimate that the rate for males post Pfizer vaccine (12-17 years) is 4-5 per million doses (dose 1) and 40-70 per million (dose 2).

  • In the younger population, what is the comparative risk of developing myocarditis following COVID-19 disease compared with mRNA COVID-19 vaccination?

    The overall incidence of myocarditis/pericarditis for all age groups remains significantly below risk of a similar condition after COVID-19 disease.

    In the 12-17 year old age group, overseas data shows the risk of developing myocarditis from COVID-19 disease is up to 6.7 times higher than developing it from COVID-19 mRNA vaccines.

    For more information please refer to:

  • As myocarditis/pericarditis associated with mRNA COVID-19 vaccines is postulated to be immune mediated, would those with existing autoimmune disease be at an increased risk compared to the general public?

    Myocarditis/pericarditis following mRNA vaccines appears to be idiosyncratic at this stage, with no clear risk factors. Thus, there is no indication of increased risk in those with underlying autoimmune disease.

  • Does the interval between the 1st and 2nd dose of mRNA vaccine have any impact on the rates of myocarditis/pericarditis after COVID-19 mRNA vaccines?

    There is no current evidence to suggest that the interval between doses of COVID-19 mRNA have any impact on rates of this AEFI. Evaluation of this is ongoing both nationally and internationally.

  • What is the long term sequelae for these myocarditis/pericarditis cases related to COVID-19 mRNA vaccines?

    Current data shows that myocarditis/pericarditis associated with COVID-19 mRNA vaccines generally have a good outcome, with the majority of cases making a full recovery in the medium term.

    There are ongoing studies looking at long term outcomes for these patients.

  • If the risks of pericarditis and myocarditis is higher in the young people, why isn’t Vaxzevria (AstraZeneca) recommended?

    The risk of Tier 1 thrombosis with thrombocytopenia syndrome is higher in younger age groups, with significant associated mortality and morbidity. Therefore, it is not the preferred vaccine for these age groups as per ATAGI recommendations.

    Importantly, most cases of myocarditis/pericarditis associated with mRNA COVID-19 vaccines have made a good recovery.

Authors: Daryl Cheng (Medical Lead, MVEC), Rachael McGuire (MVEC Education Nurse Coordinator) and Francesca Machingaifa (MVEC Education Nurse Coordinator)

Reviewed by: Rachael McGuire (MVEC Education Nurse Coordinator) and Francesca Machingaifa (MVEC Education Nurse Coordinator)

Date: October 26, 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.