Vasovagal Episode or Anaphylaxis
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Vasovagal Episode or Anaphylaxis after vaccination - the difference between a vasovagal episode or anaphylaxis for immunisation providers
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).
Vasovagal — Immediate, usually within minutes of, or during, receiving the vaccine
Anaphylaxis — Usually within 15 minutes but can occur within hours of receiving the vaccine
Vasovagal — Normal respiration, may be shallow but not laboured
Vasovagal — Generalised pallor, cool clammy skin
Vasovagal — Nausea, vomiting
Anaphylaxis — Abdominal cramps, diarrhoea, nausea and /or vomiting
Vasovagal — Feels faint, light-headed
Anaphylaxis — Sense of severe anxiety and distress
Rapid intramuscular (IM) administration of adrenaline is the foundation for treatment of anaphylaxis.
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.