Vaccine Allergy? Skin testing and challenge at a tertiary pediatric hospital in Melbourne, Australia

Publication date: Available online 23 January 2019

Source: The Journal of Allergy and Clinical Immunology: In Practice

Author(s): Abigail Cheung, Sharon Choo, Kirsten P. Perrett

Abstract

Background

The rate of true vaccine allergy is unknown. Children with potential IgE-mediated Adverse Events Following Immunization (AEFI) should undergo allergy investigation that may include skin testing or challenge. Previous protocols tend to be highly conservative and often suggest invasive testing for all; a practice not evidence based, technically difficult and unpleasant in children. It has more recently been suggested that skin testing may be restricted to those with allergic-like events within the first hour and those with history of anaphylaxis.

Objective

We aimed to describe the outcome of vaccine skin testing and challenge in children referred to a tertiary pediatric hospital with a potential IgE-mediated AEFI. Secondary aims were to identify any significant risk factors for vaccine allergy.

Methods

A retrospective review of all children (< 18 years), who underwent vaccine skin testing (skin prick test (SPT) or intradermal (IDT)) or challenge over a 5-year period (May 1, 2011 to April 30, 2016) at the Royal Children's Hospital Melbourne.

Results

There were 109 admissions in 74 children. 8% (6/74) of children had confirmed vaccine allergy (positive skin testing or challenge to the index vaccination). Two had positive IDT to suspect vaccine but challenge negative to alternative brand vaccine. Two had negative IDT but subsequent positive challenge and two had immediate urticaria on challenge without prior skin testing. Children with an AEFI < 15 minutes post vaccination or with grade 1 anaphylaxis at any time post vaccination had higher rate of true vaccine allergy (9.6% vs 4.5%).

Conclusion

The vast majority of children (92%) presenting with a potential IgE-mediated AEFI are able to tolerate challenge to suspect vaccine without reaction. We present our investigation protocol recommending skin testing in all children with anaphylaxis and challenge with suspect vaccine if negative testing or previous non-anaphylactic potential IgE mediated AEFI.

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