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Vaccination Programs: Immunization Information Systems


What the Task Force Found

About The Systematic Review

The Task Force finding is based on evidence from a systematic review of 240 studies (108 published studies and 132 conference abstracts; search period January 1994 - April 2011). Included studies represented IIS-supported interventions (e.g., client reminder and recall systems) and described IIS program activities and experiences. The systematic review was conducted on behalf of the Task Force by a team of specialists in systematic review methods, and in research, practice, and policy related to increasing appropriate vaccination.


Immunization information systems now operate in all but one U.S. state. Most IIS serve all children, adolescents, and adults in the jurisdiction (CDC this link is to an external website).

Summary of Results

Studies were assigned to nine categories for evidence assessment.

  • Overall evidence on effectiveness
    • A published study from Australia examined change in vaccination rates following adoption of a national IIS. Although vaccination rates steadily increased, change likely reflected increased participation rates driven by incentive payments for both families and vaccination providers.
    • A cross-sectional study conducted in the United States evaluated the association between practice use of an IIS and likelihood of children being up-to-date. Practices using an IIS did not have significantly higher coverage levels than those practices not using an IIS.
  • IIS-supported interventions to increase vaccination rates
    • Client reminder and recall systems:
      • Median absolute improvement in vaccination rates: 6 percentage points (interquartile interval: 4 to 7 percentage points; 13 studies, 16 study arms)
      • An additional 17 descriptive studies reported client reminder and recall activities using the IIS.
    • Provider assessment and feedback:
      • Median absolute improvement in vaccination rates: 9 percentage points (range of values: 5 to 15 percentage points; 5 studies)
      • An additional 10 descriptive studies reported the use of IIS to support the conduct of these interventions.
        • Provider reminders (also referred to as clinical decision support for immunizations, or CDSi):
      • Absolute increase in vaccination rates: 14 percentage points (one study)
      • Many IIS in the United States have built-in reminders for vaccination providers when a client record is consulted.
  • IIS use in vaccination-related decisions by clinicians, schools, and health care systems
    • No studies evaluated the use of IIS by vaccination providers at the clinic level.
    • Ten studies described use of IIS in school settings.
    • Four studies described the use of a state IIS by a health care system. Three of the studies described using IIS data for quality measurements, including HEDIS (Healthcare Effectiveness Data and Information Set).
  • IIS use in public health response
    • Eighteen studies described use of IIS to respond to outbreaks of vaccine-preventable disease, including:
      • Targeted recalls of unvaccinated patients
      • Retrospective review of vaccine uptake to monitor provider adoption of revised vaccination recommendations
      • Guiding decisions around 2009 H1N1 influenza vaccine distribution and client management
      • Three studies described use of IIS to respond to a public health emergency situation, including two that detailed the use of IIS to screen vaccination histories of displaced persons following Hurricane Katrina in order to prevent costs associated with administering unneeded vaccines.
  • IIS use to support vaccine management
    • Fourteen studies described the use of IIS in the process of vaccine supply management, distribution, and accountability; ten involved doses distributed as part of the U.S. Vaccines for Children Program this link is to an external website.
  • IIS to assess vaccine safety and effectiveness
    • Seventeen studies described use of IIS in assessment of, or response to, vaccine safety issues or in evaluation of vaccine effectiveness.
  • IIS as a tool for public health decision support
    • Included studies described a range of IIS surveillance capabilities including:
      • Coverage assessments for specific vaccines (51 studies)
      • Investigations of vaccination rates among high risk subsets of the population (32 studies)
      • The ability to monitor the uptake of new vaccines (16 studies)
  • IIS integrated with other child health information systems
    • Eight studies discussed integration of additional child health data (e.g. blood-lead levels, early hearing detection) into an existing IIS.
  • IIS contributing to change in documentation
    • Twenty-four studies compared the completeness of individual IIS vaccination records with some other immunization data source (e.g. medical records, parental report).

Summary of Economic Evidence

The economic review is based on evidence from 14 studies (12 published papers and 2 government reports; search period January 1994 – March 2012). Included studies evaluated the cost of IIS (9 studies; 7 assessed system costs, and 2 assessed the cost of exchanging immunization data), benefits of IIS (9 studies), and cost-benefit ratios (4 studies). All studies provided information about IIS implemented in the United States and focused on pediatric immunizations.

Of the seven studies that assessed system costs, six evaluated systems implemented from 1997 to 2002. Cost and benefit data from these studies may be less applicable today owing to changes in system technology, data exchange methods, availability of vendor support, and system functionalities. It is likely, however, that more up-to-date estimates would support the findings of cost savings in this review.


Results of this review are broadly applicable to IIS implemented in the United States for use with the childhood vaccination series. This is especially true as systems achieve levels of provider and client participation demonstrated by Sentinel Site programs.

Evidence Gaps

Each Community Preventive Services Task Force (Task Force) review identifies critical evidence gaps—areas where information is lacking. Evidence gaps can exist whether or not a recommendation is made. In cases when the Task Force finds insufficient evidence to determine whether an intervention strategy works, evidence gaps encourage researchers and program evaluators to conduct more effectiveness studies. When the Task Force recommends an intervention, evidence gaps highlight missing information that would help users determine if the intervention could meet their particular needs. For example, evidence may be needed to determine where the intervention will work, with which populations, how much it will cost to implement, whether it will provide adequate return on investment, or how users should structure or deliver the intervention to ensure effectiveness. Finally, evidence may be missing for outcomes different from those on which the Task Force recommendation is based.

Identified Evidence Gaps

  • More research is needed, especially in U.S. settings, on the overall impact of IIS (or IIS activities) either on vaccination rates in the general population or on important target populations with gaps in coverage.
  • More evidence is needed to assess the usefulness of IIS for vaccination providers in clinical settings.
  • Future studies should examine participation rates and record capture based on demographic characteristics such as race and ethnicity, household income, and insurance status.
  • Future studies should attempt to quantify the frequency and reach of various IIS activities within the population.
  • More economic data are needed on the costs of implementing present-day IIS, with information detailing whether the system is developed in-house or vendor supported.
  • Additional benefits (improved efficiencies and decreased time associated with conducting provider reminder/recall functions, provider assessment and feedback efforts, improved vaccine supply and management, and reduced morbidity and mortality) need to be monetized to fully capture the economic returns that accrue from using an IIS.
  • As more providers create direct linkage from Electronic Health Records (EHRs) to the central IIS, more information and details are needed about the costs of this type of connection.

Study Characteristics

Studies evaluated systems in the United States (209 studies), Australia (2 studies), and other countries (5 studies).

  • 108 of the studies conducted in the U.S. (52% of the included studies) described actions and capabilities of systems within the IIS Sentinel Site program link is to an external website.
  • Most U.S. studies considered children and vaccinations within the childhood series. Only 33 studies (20% of the included studies) that reported vaccination outcomes described the use of IIS for adolescents and 12 (7%) described the use of IIS for adult populations, with most studies focused on influenza vaccination.

Of the included studies, 47 evaluated or described at least 1 of 3 specific interventions to increase vaccinations supported directly by an IIS or population-based vaccination database:

  • Client reminder and recall notices
  • Provider assessment and feedback activities
  • Provider reminder systems

Studies evaluated IIS used in various settings for different reasons:

  • 14 U.S. studies evaluated or described the use of IIS by vaccination providers, schools and day cares, or health care systems.
  • 10 U.S. studies described IIS interactions with schools and day cares.
  • 18 U.S. studies evaluated or described the use of IIS in responses to outbreaks of vaccine-preventable disease or other public health emergencies.
  • 4 studies described the use of a state IIS by a health care system.
  • 14 studies provided descriptions of the use of IIS in facilitating vaccine ordering, inventory monitoring, and vaccine-related accountability.
  • 17 studies (12 from the U.S.) described the use of IIS in assessment of, or response to, vaccine safety issues or in evaluation of vaccine effectiveness.