Most side effects from a COVID-19 vaccine are mild and transient. Reactions at the injection site such as redness, swelling, pain and systemic symptoms, like headaches, fever, muscle aches and fatigue, are very common within the first 48 hours. Serious adverse events attributable to vaccination are very rare.
For information on what to expect after vaccination: Australian Government's Department of Health and Aged Care (external site). Regularly updated vaccine safety data is also published at AusVaxSafety (external site).
Myocarditis and/or pericarditis
The Australian Technical Advisory Group on Immunisation (ATAGI) and the Cardiac Society of Australia and New Zealand (CSANZ) have recently updated the Guidance on Myocarditis and Pericarditis after COVID-19 Vaccinations (external site).
Myocarditis and/or pericarditis are rare side effects that have been associated with all brands of COVID-19 vaccine currently used in Australia. The available data suggests the risk is higher after an mRNA vaccine and is greater following Spikevax (Moderna) compared to Comirnaty (Pfizer).
Pericarditis and myocarditis after COVID-19 vaccines have been mostly reported in males aged 16-40 years of age, and mostly after the second dose. However, these conditions do occur in both females and males, at any age, and after any dose, including a third or fourth dose.
The WA Department of Health accordingly advises the following:
- Myocarditis and pericarditis following vaccination can present with atypical features, such as the absence of chest pain, or the presence of abdominal pain or other non-specific symptoms. It is important to consider myocarditis in the differential diagnosis if someone presents with ongoing non-specific symptoms in the 1-2 weeks following a COVID-19 vaccine.
- Providers should consider the potential risk of myocarditis and pericarditis when selecting a COVID-19 vaccine brand and dose interval, considering the individual’s age, gender, preferences, and any precautions in relation to specific vaccine brands.
- ATAGI recommends an 8-week interval between dose one and dose two for the Pfizer, Moderna and Novavax vaccines, particularly for males aged 12 to 39 years. This may reduce the risk of myocarditis and/or pericarditis following vaccination.
- Most myocarditis cases linked to COVID-19 vaccination have required hospitalisation, with most cases having a relatively mild and self-limiting course. Fatal cases have been reported, including in females.
- Patients with confirmed myocarditis should be admitted to hospital for cardiac monitoring, until the cardiac biomarker levels have peaked, and symptoms have improved.
- Pre-existing cardiac conditions are not regarded as a contraindication to vaccination.
- People with a history of any of the following conditions can receive an mRNA vaccine (e.g. Comirnaty or Spikevax) but should consult a GP, immunisation specialist service or cardiologist about the best timing of vaccination and whether any additional precautions are recommended:
- Recent myocarditis or pericarditis (within the last 3 months)
- Acute rheumatic fever or acute rheumatic heart disease (i.e., with evidence of active inflammation)
- Acute decompensated heart failure
For more information see ATAGI’s COVID-19 vaccination: Guidance on myocarditis and pericarditis after COVID-19 vaccines (external site).