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Vaccine Safety > Issues of Interest > Multiple Vaccines 
Institute of Medicine (IOM) Report
Immunization Safety Review: Multiple Immunizations & Immune Dysfunction
Released February 20, 2002

Contents of this page:

Related links/pages:

Overview of the IOM Report

In 2000, the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) asked the Institute of Medicine (IOM) to establish an independent expert committee to review hypotheses about existing immunization safety concerns. The first report on Measles, Mumps, Rubella (MMR) vaccine and autism was released in April 2001 and the second report on thimerosal-containing vaccines and neurodevelopmental disorders was released in October 2001. On February 20 2002, the IOM released its third report which addressed multiple immunizations and immune dysfunction.

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. CDC and NIH welcome this report, which is a helpful contribution towards a better understanding of this issue.  CDC and NIH are most grateful to the individual scientists on the IOM Committee and IOM staff members for their dedicated and valuable service to the continued integrity of our national immunization system.

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.

The Committee recommends limited but continued public health attention to this issue in the form of policy analysis, research and communication strategy development. However, the Committee does not recommend a review by national and federal vaccine-related advisory groups of the licensure or schedule of administration of vaccines on the basis of concerns about immune dysfunction.

Next Steps
The Committee has made helpful recommendations about policy, research and communication issues which are important to resolve outstanding issues related to the hypothesis that multiple vaccinations increase the risk for immune dysfunction. These recommendations will be considered in depth by Public Health Service agencies over the next several months.

Links to actual IOM report

The IOM report and the news release are available on the Web at

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This page last modified on February 21, 2002


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