Neurologic complications of immunization.

In the United States and many other developed countries, active immunization of children has virtually eliminated poliomyelitis, measles, rubella, tetanus, and other diseases, such as disease due to Haemophilus influenzae type b. Individual vaccines can produce systemic or neurologic reactions ranging from minor events, such as pain and erythema at the injection site, to major complications, such as seizures, shock, encephalopathy, or death. Immunization programs have also generated considerable controversy, as witnessed by recent concerns regarding the relationship between vaccines or their constituents and autism or multiple sclerosis. This review summarizes current information regarding vaccines, the diseases that they prevent, and the potential relationships between vaccines and neurologic disease.