Allergies to vaccines in children

Abstract

The aim of this article is to review the allergic reactions to infectious disease vaccines in children and offer guidance on how to practically approach the question of a possible allergic reaction to a vaccine. Allergies to vaccines occur at an estimated rate of 1-2 in 1,000,000 vaccine doses. For the most part concerns over possible allergies to vaccines are usually not supported by the appropriate scientific facts and are exaggerated by ignorance, fear and irrational beliefs. If an allergic reaction to a vaccine is believed to have occurred, the first step is to link the clinical symptoms to the vaccine administration. Urticaria, angioedema, wheezing and hypotension occuring within 30 minutes after vaccine administration point to a probable severe IgE-mediated reaction. Most vaccine constituents may cause the immediate type allergic reaction: stabilizers (gelatin, dextran), remnants of culture media (ovalbumin, yeast), latex from vial stoppers, antimicrobial agents added to maintain sterility, the least common being microbial antigens and preservatives. Prick and intradermal testing with whole vaccine and with specific constituents should be performed within 3-12 weeks following the reaction. In vitro tests (specific IgE) should be done if available. Positive in vivo or in vitro tests do not necesssarily preclude further vaccination, especially if it is considered vital or outweighing the potential risks. However, decision should be made on a case by case basis by a qualified allergist. Fractionated or graded dose protocols are available for implementation in day care or hospital settings. Conclusion – Systemic IgE mediated allergy to vaccines is rare in children. If it occurs a full list of vaccine constituents should be considered and appropriate allergological testing performed.