Infant immunizations not shown to be harmful to infants' systems

Although most people realize the benefits of vaccinations, a recent survey showed that approximately one-quarter of parents believe that infants get more vaccines than are good for them, and that too many immunizations could overwhelm an infant's immune system.

On Feb. 20, 2002, the Institue of Medicine (IOM) released its latest report in a series on vaccine safety, "Immunization Safety Review: Multiple Immunizations and Immune Dysfunction."

The IOM's Immunization Safety Committee reviewed eight studies of the relationship between multiple vaccinations and Type 1 diabetes, the autoimmune form of the disease. All eight studies consistently demonstrated that multiple immunizations had no effect on the incidence of Type 1 diabetes, leading the committee to reject the notion that multiple vaccinations cause an increased risk of the disease.

The IOM also looked at the results of seven studies, which, despite some variations and limitations, consistently showed that multiple vaccinations either had no effect on the risk of infection or provided some degree of protection against infection. The IOM concluded that multiple immunizations do not increase the risk of young children developing various infections, ranging from colds and ear infections to pneumonia and meningitis.

The IOM also examined five studies looking at multiple vaccinations and their potential to cause allergic diseases, which reflect a hypersensitivity of the immune system to relatively harmless agents in the environment, like pollens, dust mites, insect venom, and specific foods. Some, but not all, of these studies suggested that certain vaccines increase the risk of developing allergic disorders. However, methodological weaknesses and inconsistent findings among the studies, led the committee to conclude that there is inadequate evidence to either accept or reject a causal relationship between multiple immunizations and increased risk of allergic diseases, particularly asthma.

Finally, the IOM recommended that the U.S. Department of Health and Human Services convene an expert panel to examine parents' perceptions of vaccine risks and benefits in order to develop better communication tools for them and their doctors.

The IOM Immunization Safety Review Committee's most important conclusions were:

1. A review of the available scientific evidence does not support the hypothesis that the infant immune system is inherently incapable of handling the number of antigens that children are exposed to during routine immunizations,
2. The epidemiologic evidence (i.e., from studies of vaccine-exposed populations and their control groups) favors rejection of a causal relationship between multiple immunizations and increased risk for infections or for type 1 diabetes mellitus,
3. The epidemiologic evidence regarding increased risk for allergic disease, particularly asthma, was inadequate to accept or reject a causal relationship.