The available data indicate that the immunization schedule for children through age 6 years is safe, according to a report released by the Institute of Medicine.
The report identifies areas that need more research, however, and makes recommendations about how to study safety issues if safety signals related to the vaccine schedule are identified. The report also concludes that more research is needed on the perception of vaccines and how to improve communications, recommending that the National Vaccine Program Office "systematically collect and assess evidence regarding public confidence in and concerns about the entire childhood immunization schedule, with the goal to improve communication with health care professionals, and between health care professionals and the public regarding the safety of the schedule."
The report, titled "The Childhood Immunization Schedule and Safety: Stakeholder Concerns, Scientific Evidence, and Future Studies," was released on Jan. 16. Unlike previous IOM vaccine-related reports, this report focuses on the safety of the childhood vaccination schedule overall, not the safety of individual vaccines.
The 13-member multidisciplinary committee was charged with reviewing the scientific data on health-related outcomes and safety issues associated with the vaccination schedule for children through age 6 years, which entailed public meetings to collect information, with participation from clinicians, federal and state agencies, international public health agencies, advocacy groups, vaccine manufacturers, and other stakeholders. The committee conducted an extensive literature review on vaccine-associated health outcomes and safety of the vaccine schedule, looking at issues that included the number of vaccines, frequency of administration, spacing between doses, cumulative doses, age of recipient, order of vaccine administration, as well as asthma, hypersensitivity, diabetes, and other autoimmune diseases, seizures and epilepsy, autism and other developmental disorders, and other outcomes.
"After our review, our committee found no evidence that the childhood immunization schedule is not safe," committee member Dr. Alfred Berg, professor in the department of family medicine, University of Washington, Seattle, said during a briefing held to announce the release of the report. "The evidence repeatedly points to the health benefits of the recommended schedule, including protecting children and the community from serious and life-threatening diseases."
The recommendations made to the national vaccine program office include standardizing definitions to use in future research, including defining outcomes and potentially susceptible populations. Dr. Berg added that, although there was no basis for concern about the safety of the current schedule, the committee recommended that stakeholder concerns about vaccine safety should be systematically assessed and used to help set priorities for future research when safety signals are detected.
The committee’s review "did not find reveal a base of evidence suggesting that the childhood immunization schedule is linked to autoimmune diseases, asthma, hypersensitivity, seizures or epilepsy, child developmental disorders, learning disorders or developmental disorders, or attention deficit or disruptive behavior disorders," the report concluded. However, although there was no evidence "to justify safety concerns," the report points out that "perceptions dictate parental support and actions," and that further study focused on understanding the perceptions of stakeholders and how their perceptions are formed "may help improve awareness and education efforts." With no epidemiologic or biological evidence to support safety concerns, the concerns alone "do not warrant the initiation of new high-cost randomized controlled trials," the committee concluded.
The report points out that the Vaccine Safety Datalink (VSD), a safety surveillance system, is currently the best tool for evaluating the vaccine safety, although it only tracks people in eight states and does not adequately represent low-income and minority populations. The committee is optimistic about the potential for other surveillance systems that are being developed in their ability to monitor vaccine safety, namely, two Food and Drug Administration programs that will enhance the collection of safety data on vaccines: the Sentinel Initiative program, and the new Post-Licensure Rapid Immunization Safety Monitoring program, which have potential to analyze vaccine exposures and adverse events "with a greater degree of statistical power," according to the report.
Committee member Dr. Elena Fuentes-Afflick, chief of pediatrics at San Francisco General Hospital, said that it is important to maintain and expand the monitoring system to identify rare complications or safety issues affecting particular subgroups. And if there is evidence suggestive of a safety issue, the report outlines research strategies and approaches that can be used to assess whether it is related to the individual vaccine or immunization schedule, she said. “It’s very difficult to do a study which would allow you to state how much of a difference is related to either an individual vaccine or to the vaccine schedule.” She noted that the report recommends against conducting a randomized controlled trial in this situation, because of feasibility, practical and ethical concerns related to a randomized trial that would compare vaccination to no vaccination.