Epidemiology of autoimmune reactions induced by vaccination

In order for vaccinations to 'work', the immune system must be stimulated. The concern that immunizations may lead to the development of autoimmune di sease (AID) has been questioned. Since AID occur in the absence of immuniza tions, it is unlikely that immunizations are a major cause of AID. Epidemio logical studies are needed, however, to assess whether immunizations: may i ncrease the risk in some susceptible individuals. This paper discusses the evidence for and against vaccination as a risk factor for AID. Evidence for immunizations leading to AID come from several sources including animal st udies, single and multiple case reports, and ecologic association. However more rigorous investigation has failed to confirm most of the allegations. Unfortunately the question remains difficult to address because for most AI Ds, there is Limited knowledge of the etiology, background incidence and ot her risk factors for their development. This information is necessary, in t he absence of experimental evidence derived from controlled studies, for an y sort of adequate causality assessment using the limited data that are ava ilable. Several illustrative examples are discussed to highlight what is kn own and what remains to be explored, and the type of epidemiological eviden ce that would be required to better address the issues. Examples include th e possible association of immunization and multiple sclerosis (and other de myelinating diseases), type 1 diabetes mellitus, Guillain-Barre Syndrome, i diopathic thrombocytopenic purpura, and rheumatoid arthritis. (C) 2001 Acad emic Press.