Viral vaccination and allergy
Childhood immunisation is one of the greatest public health successes of the last century. Adverse vaccine reactions are uncommon and may be caused by the vaccine itself, by preservatives, adjuvants and stabilisers, or by contaminants acquired during the manufacturing process or administration of the vaccine. Influenza vaccine contains significant amounts of egg protein and may cause allergic reactions in egg-sensitive individuals. Adverse reactions are classified as IgE-mediated, delayed hypersensitivity reactions, or non-allergic, manifesting as pyrexia and local reactions. The history is vital in the assessment of an adverse vaccine reaction, particularly in respect of the onset of symptoms in relation to the administration of the vaccine. Skin-prick testing and intradermal testing are useful in assessing IgE-mediated reactions where future vaccination is required. The overwhelming evidence is that childhood immunisations are not causally related to asthma and allergic disease, and are safe. Influenza vaccination is recommended in asthmatics and is safe, but the evidence for its efficacy in preventing asthma exacerbations is not convincing, and it has not been shown to be cost-effective. Parents should be encouraged to have their children immunised against childhood diseases as the benefits far outweigh the risks.