immune disease that closely resembles human systemic lupus erythematosus. Animals were immunized with a protective antigen-based anthrax vaccine, alone or with various combinations of the diphtheria–tetanus (DT) vaccine; combined diphtheria, tetanus, and whole-cell pertussis (DTP) vaccine; combined diphtheria, tetanus, and acellular pertussis (DTPa) vaccine; or plague vaccine. Researchers noted that the development of autoimmune disease in the groups of animals could be accelerated or inhibited depending on the timing of the vaccination. These experiments suggest that immune stimulation by vaccination may alter the development of autoimmune disorders. As expected, such alterations may depend on the genetic susceptibility of the animal to autoimmune disease.

Conclusions on Animal Studies

Studies in animals found no difference in the degree of protective immunity with multiple vaccinations. Studies have suggested that a single high dose of an antigen or repeated stimulation with the same antigen may result in the production of autoantibodies or malignancies. However, the antigen loads in these studies far exceeded those used in human vaccine schedules with repeated vaccination. One study (Classen, 1996) did suggest that vaccination, whether single or multiple, could influence the development of autoimmune disorders in genetically susceptible animals. Thus, although it is plausible that an exaggerated immune stimulation from vaccination could lead to long-term effects of autoimmune-type disease with the attendant multiorgan system pathology, no long-term animal studies supporting this hypothesis have been reported.

Human Studies

Studies of three populations are particularly relevant to examining the effects of intensive administration of a large number of vaccinations. The first population is a group of Finnish army recruits who received many routine vaccines during the first weeks of service. The second group of studies followed laboratory workers at Fort Detrick who received an intensive vaccination program for occupational reasons. Further, the committee examined several studies of Gulf War veterans.

Finnish Army Studies

A series of studies of Finnish military recruits who received many vaccinations investigated whether intensive vaccination would stimulate the immune system to develop autoantibodies (Aho et al., 1962, 1967). The autoantibodies measured in the studies were rheumatoid factor (RF) and immunoconglutinin (IC). All servicemen were healthy during the observation period. Blood samples were drawn before vaccination and on two instances afterwards. Table 7.2

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