and summarized information on the association between aspects of the immunization schedule and specific health conditions already available in the peer-reviewed literature. The health outcomes that the committee chose to review were selected on the basis of its examination of the peer-reviewed literature, previous IOM vaccine safety studies, and public presentations at open meetings of the committee. The number of studies of aspects of the schedule varied; for some outcomes, several studies examining the cumulative effects of vaccines and adjuvants or preservatives were found; for other outcomes, very few studies were found. The committee’s methods and reviews are briefly summarized below.


The committee members and IOM staff conducted searches of the English-language literature published in the past 10 years (2002 to 2012) for children ages 0 to 18 years using the medical subject headings (MeSH) “immunization” or “vaccines,” combined with the following terms for health outcomes of interest:

  • “autoimmune diseases” (which captures “diabetes mellitus, type 1”),
  • “asthma,”
  • “hypersensitivity,”
  • “seizures” or “epilepsy” or “febrile seizures,”
  • “child developmental disorders, pervasive” (which captures “autistic disorders”),
  • “learning disorders” or “communications disorders” or “intellectual disability” or “developmental disorders,”
  • “attention deficit and disruptive behavior disorders,” and
  • “tics” or “Tourette’s syndrome.”

The literature published in the past 10 years was chosen to fill the gap since the 2002 IOM review and because several changes to the immunization schedule have been made since 2000 (e.g., addition of the pneumococcal and rotavirus vaccines). Studies more than 10 years old would be of outcomes that occurred after use of an immunization schedule with less resemblance to the current one.

All searches were run against the Ovid MEDLINE database (1950 to present). The search excluded reviews, commentaries, editorials, and similar publications. The conventional electronic searches were supplemented with articles identified by committee members and staff and articles that were noted during committee discussions and public presentations at open meetings. Commentaries and reviews were reviewed but not analyzed in the

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