Anaphylaxis is a serious systemic allergic reaction that is potentially life-threatening. Anaphylaxis has a rapid onset and requires immediate adrenaline administration. Guidance for anaphylaxis management post-vaccination can be found in the
Australian Immunisation Handbook.
Diagnosis of anaphylaxis is based on clinical symptoms* and history of a recent exposure of a probable trigger (most commonly foods or drugs, but very occasionally, vaccination).
*Symptoms of anaphylaxis are:
There are some laboratory investigations that may support a diagnosis of anaphylaxis. In the case of death, laboratory investigations may provide evidence towards a cause of death, including anaphylaxis.
Cells involved in anaphylaxis include mast cells and basophils, although though mast cells predominate. Upon activation of these cells, degranulation causes release of a range of mediators from inside the cell to the extracellular environment. The most well-studied mediators that are released from the cell are tryptase and histamine. In practice, histamine has limited value for investigation purposes.
Clinical presentations that can mimic anaphylaxis, but that do
not usually result in raised tryptase levels include vasovagal reactions, septic shock or seizures.
Serum tryptase (also known as mast-cell tryptase) may be useful for ruling in anaphylaxis and so should be collected for all suspected cases, however it is much less useful in ruling it out.
The diagnosis of anaphylaxis is made based on clinical grounds. The majority of anaphylaxis secondary to the Pfizer – BioNTech (Comirnaty) COVID-19 vaccination occurs within 15 minutes of administration. Vaccine recipients who have a history of severe allergy will be observed for at least 30 minutes following vaccination.
Serum tryptase should be collected where anaphylaxis is clinically suspected.
If further advice is required to support investigations following suspected anaphylaxis, the NSW Immunisation Specialist Service may be contacted for urgent advice on
1800 679 477.
Serious adverse events following immunisation (AEFI) are notifiable conditions in NSW. Healthcare providers are required to report any serious AEFI to NSW Health and the Therapeutic Goods Administration. More information is available on
Adverse events following immunisation (AEFI).
*Make a mandatory AEFI report, or for advice on whether an event is notifiable. 1300 066 055 – key in the postcode of residence for the relevant public health unit
Operating hours: Monday to Friday 8:30am – 5pm Email: MOH-AEFI@health.nsw.gov.au
Advice on the investigation or clinical management of a serious AEFI1800 679 477
Operating hours: Monday to Friday 9:00am – 5pm
*urgent advice on the clinical management of serious AEFI
Through the Children's Hospital Westmead switchboard:
02 9845 0000.