Les réactions allergiques et pseudo-allergiques aux vaccins

Diagnosis of Arthus-type reactions is based on clinical history and specific IgM-IgG anti-toxoid determination. For other local reactions, diagnostic value of non-immediate responses in skin tests varies with clinical symptoms and substances involved. Immediate responses in skin tests and specific IgE determination have good diagnostic and/or predictive value in anaphylaxis and immediate/accelerated urticaria/angioedema to toxoid-, pneumococcus-, and egg- and gelatin-containing vaccines. Diagnosis of reactions to dextran in BCG is based on specific IgM-IgG determination. Most non-immediate generalized reactions result from non-specific inflammation, except for gelatin-containing vaccines, but diagnostic value of immunoallergological tests with the vaccines and gelatin are controversial. Withholding booster injections is advised if specific IgM-IgG levels are high. If the levels are low, sequential injections of vaccines containing a single vaccinating agent are usually tolerated. However, injections of the vaccine should be performed using a « desensitization » procedure in patients reporting anaphylaxis and immediate/accelerated urticaria/angioedema.