Reacciones adversas a vacunas

Abstract

Adverse reactions to vaccines are highly varied, ranging from mild local reactions to fatal outcomes. In the last few years many adverse reactions have been attributed to vaccines, often without justification. In agreement with the World Health Organization, these reactions can be classified as follows, depending on the cause: vaccination-induced reactions (due to an effect of the vaccine itself or to an idiosyncrasy); reactions due to errors in storage, manipulation and/or administration; and coincidental reactions (no causal relationship with the vaccine). Hypersensitivity reactions fall into six categories, depending on the causative agent: reactions due to some component of the infectious agent or one of its products; reactions due to adjuvants: aluminium hydroxide; reactions due to stabilizers: gelatin; reactions due to preservatives: thiomersal; reactions due to antibiotics: neomycin; and reactions due to a biological culture medium: chicken embryo cells. Allergic children should not be excluded from the normal vaccine calendar. Immunologically, allergic individuals are more susceptible to infection and to microbial and viral diseases, which often play an aggravating role. Rubella, whooping cough, and influenza usually exacerbate respiratory allergies. Non-vaccination carries a marked risk of contracting serious diseases such as poliomyelitis, tetanus, and diphtheria, etc. In a not too distant future, the techniques of genetic recombination and monoclonal antibody production will allow the creation of vaccines from organisms that cannot be cultivated in the laboratory or that produce small quantities of antigen. These techniques will also lead to identification of the antigens with the greatest immunogenic power and, consequently, to extremely pure vaccines. The adverse reactions to vaccines referred to our service account for between 0.59 % and 1.27 % of first visits in the last three years. We recorded a total of 48 adverse reactions to vaccines. Of these, 44 were attributed to the tetanus vaccine (92 %), 2 to the measles-mumps-rubella vaccine (4 %) and 2 to the meningitis A and C vaccine (4 %). Clinical features consisted of urticaria (11 cases), urticaria with angioedema (7 cases), pseudo-shock (5 cases), fever and urticaria (4 cases), local reactions (4 cases), persistent crying with exanthema (3 cases), giant local reactions with angioedema of the limb (3 cases), anaphylaxis (3 cases), fever > 39.5 C (2 cases), bronchospasm (1 case), and severe atopic dermatitis (1 case).A regimen of hyposensitization to tetanus toxoid was required in 20 patients (45 %); in three, this could not be completed due to generalized urticaria but all the patients presented protective titers with diluted vaccine.