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.
Of note, respiratory symptoms (e.g. cough, runny nose etc.) are not side effects of the vaccine. People with respiratory symptoms should be tested for COVID-19.
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 link).
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).
Adverse events after COVID-19 vaccine Vaxzevria (AstraZeneca)
People who have had the first dose of AstraZeneca without any serious adverse effects can safely be given the second dose, including adults under 60 years.
Mixed dosing
It is recommended people have the same vaccine brand for the first and second dose.
However, an alternative vaccine can be offered for the second dose in some circumstances, including:
- Severe side effects after the first dose - there are medical contraindications or precautions to a vaccine,
- Overseas vaccines - the original vaccine is not available in Australia,
- Lack of access - a person is unable to access a particular vaccine
- Personal preference - a person is not accepting of a second dose of the same brand
If you have questions about switching brands between your first and second dose of COVID vaccine you should discuss it with your health care provider.
For further information, see COVID-19 vaccination – ATAGI Clinical advice on the use of a different COVID-19 vaccine as the second dose (external site).