Jan 17, 2013 (CIDRAP News) – An Institute of Medicine (IOM) review of the safety of the US childhood vaccine schedule turned up no signs that it is unsafe and found that existing vaccine safety databases are best poised—with a few tweaks—to further explore additional questions, according to a report yesterday.
IOM scientists conducted the study based on a request from the Department of Health and Human Service (HHS) over concerns about the quantity and timing of vaccines. The immunization schedule recommended by federal health officials is designed to protect kids from 14 different pathogens at a time when they're most vulnerable to the diseases.
The IOM noted in its 175-page report that more than 90% of kids enter kindergarten with most of the recommended immunizations, but some parents have aired worries that the vaccine schedule is too "crowded" and have asked doctors for more flexible immunization timing to space out or delay some of the doses. According to current recommendations, children may receive up to 24 immunizations by their second birthday and up to five injections during a single office visit.
The IOM said the study is its first to specifically explore the entire child vaccination schedule. The group examined the scientific literature and sought feedback from several stakeholder groups, including researchers, advocacy groups, parents, the public, and federal agencies.
They found no links between adverse events and the immunization schedule and said that the federal government's existing safety systems provide further confidence that the current schedule is safe.
IOM researchers considered alternative methods for answering safety questions, such as comparing health outcomes of unvaccinated kids with vaccinated youngsters. The group, however, wrote that a randomized clinical trial would raise ethical problems and an observational study would be less likely to reveal conclusive differences between the two groups, because less than 1% refuse all vaccinations and closely matching vaccinated and unvaccinated kids would be extremely difficult.
The Vaccine Safety Datalink, a collaboration between the Centers for Disease Control and Prevention and nine managed care organizations, is the best system for studying the safety of the vaccine schedule, the group stated. But it has some limitations that make it difficult to tease out health difference among kids immunized with alternate vaccination schedules, the IOM said.
The system, though, could be modified to ask additional questions, improve the demographic information, and include more diversity in study populations, the investigators said.
New federal data collection and surveillance system have the potential to monitor rare adverse events associated with the vaccination schedule, the committee said. One is the Sentinel Initiative program being developed by the Food and Drug Administration (FDA) to monitor the safety of approved drugs and medical products.
Another is the FDA's new Post-License Rapid Immunization Safety Monitoring Program, which has the potential to track vaccine exposures and adverse events with greater statistical power, according to the report.
In the years ahead, the childhood immunization schedule might become more complex as new vaccines are developed, the IOM said, adding that it supports HHS efforts to involve stakeholders in discussions about the benefits of and concerns about the childhood immunization schedule.
Jan 16 IOM report
Jan 16 IOM press release