Allergic and non-allergic hypersensitivity reactions to vaccines

Most frequent allergic-(like) reactions to vaccines are local (non-immediate inflammation resulting from Arthus phenomenon or, most frequently, non-specific, and, less frequently, persistent nodules, sterile abcesses and eczema). Generalized reactions are less frequent, but more worrying, than local reactions. The results of studies based on skin tests, specific antibody levels (IgM/IgG, IgE) determinations, and booster injections, show that most reactions do not result from vaccine hypersensitivity, except for anaphylactic and/or immediate reactions for which immediate-reading skin tests and specific IgE determinations (when available) have a good diagnostic value. In patients with proven or highly suspected allergy, withholding of injection of the vaccine is advised if vaccination or booster immunization is not essential (children with high levels of serum specific IgM/IgG, vaccination not compulsory, high risk of reaction versus low benefit of the vaccine). If vaccination is compulsory or essential, immunization based on sequential (intramuscular) injections of vaccines containing a single or a limited number of vaccinating agents is usually well-tolerated in children reporting local inflammatory reactions or mild to moderately severe generalized reactions. In children with IgE-mediated urticaria/angioedema and anaphylaxis, the responsible vaccine should be injected using a "desensitization" procedure, performed under medical supervision in the hospital. Although non validated, intramuscular injection of the vaccines with large and long needles may prevent other reactions to vaccines, such as persistent nodules, sterile abcesses, eczemas and naevi with hypertrichosis. (C) 2012 Elsevier Masson SAS. All rights reserved.