Distinguishing vasovagal episodes from anaphylaxis reactions following immunisation
Immunisation providers must be able to distinguish between a vasovagal episode (faint), convulsion and anaphylaxis.
A vasovagal episode (faint) is relatively common after the vaccination of adults and adolescents, but infants and children rarely faint.
Anaphylaxis following routine vaccination is very rare, but can be fatal.
Sudden loss of consciousness in young children should be presumed to be an anaphylaxis, particularly if a strong central pulse is absent. A strong central pulse (carotid) persists during a vasovagal episode or convulsion.
For a printable version, download the Vasovagal Episode or Anaphylaxis chart (PDF 261KB).
|Onset||Immediate, usually within minutes of, or during, receiving the vaccine||Usually within 15 minutes but can occur within hours of receiving the vaccine|
|Respiratory||Normal respiration, may be shallow but not laboured||
Generalised pallor, cool clammy skin
|Gastrointestinal||Nausea, vomiting||Abdominal cramps, diarrhoea, nausea and /or vomiting|
|Neurological||Feels faint, light-headed||Sense of severe anxiety and distress|
Management of anaphylaxis
Rapid intramuscular (IM) administration of adrenaline is the foundation for treatment of anaphylaxis.
- If patient unconscious, place on left side and maintain airway.
- If patient conscious, place in supine position, elevate legs (unless results in breathing difficulties).
- If showing signs of anaphylaxis give adrenaline by deep intramuscular injection into the anterolateral thigh. Must not be given intravenously.
- Call for assistance. Never leave patient alone.
- Administer oxygen if available by face mask at a high flow rate.
- If no improvement in patient’s condition within 5 minutes, repeat doses of adrenaline every 5 minutes until condition improves or medical assistance arrives
- Check breathing. If absent, commence basic life support or appropriate CPR as per the Australian Resuscitation Council guideline.
- Transfer to hospital for further observation and treatment.
- Document the event including time(s) and dose(s) of adrenaline administered.
Adrenaline 1:1000 = 0.01 ml/kg (0.01mg/kg) deep IM injection in thigh
Less than 1 year (approx 5-10 kg) 0.05 to 0.1mL
1 to 2 years (approx 10 kg) 0.1 mL
2 to 3 years (approx 15 kg) 0.15 mL
4 to 6 years (approx 20 kg) 0.2 mL
7 to 10 years (approx 30 kg) 0.3 mL
10 to 12 years (approx 40 kg) 0.4 mL
Greater than 12 years and adults, including pregnant women (over 50kg) 0.5 mL
Use a 1 mL syringe to accurately measure the dose.