After identifying key stakeholders, the committee reviewed the most frequently expressed concerns related to the safety of the immunization schedule from three primary sources of information: the current literature, online postings, and public testimony.

The committee reviewed all the information that interest groups, individuals, and researchers provided through the online submissions and in public testimony at the committee meetings and throughout the study period. Even before the first committee meeting, the committee received online testimony as well as many e-mail messages. The committee held three public meetings that included information-gathering sessions and a session during which it heard public testimony. During the three public meetings, the final hour was reserved for stakeholders to share their concerns related to the committee’s charge. Throughout the study, the committee also reviewed media coverage and scientific articles related to the safety of the immunization schedule. However, the committee based its review of the safety of the immunization schedule on information reported in the scientific literature.

The literature review focused on the recommended childhood immunization schedule and yielded an extensive body of scientific articles, reports in the popular media, reviews, and summaries. Because the committee’s study period was limited (no longer than 12 months), the committee established priorities to identify and review the most common and noteworthy stakeholder concerns about the safety of the childhood immunization schedule.


The committee used the Ovid MEDLINE database to search the scientific literature published within the past 10 years (2002 to 2012). Multiple comprehensive searches were used to identify references that described stakeholder concerns and analyzed health outcomes after immunization according to the recommended childhood immunization schedule. The committee focused on articles published in the past 10 years because the childhood immunization schedule has been modified several times as new vaccines have been approved and incorporated into the schedule. Concerns related to the 2001 recommended childhood immunization schedule are likely to be different from concerns related to 2012’s schedule, which recommends additional immunizations for children. Because the committee’s task was to assess the safety of the immunization schedule rather than the safety of individual vaccines, the literature searches did not include articles that focused on a single vaccine. The committee’s review included peer-reviewed publications such as scientific articles, reviews, commentaries,

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