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Increasing Appropriate Vaccination: Immunization Information Systems

Immunization information systems (IIS) are confidential, population-based, computerized databases that record all immunization doses administered by participating providers to persons residing within a given geopolitical area.

  • At the point of clinical care, an IIS can provide consolidated immunization histories for use by a vaccination provider in determining appropriate client vaccinations.
  • At the population level, an IIS provides aggregate data on vaccinations for use in surveillance and program operations, and in guiding public health action with the goals of improving vaccination rates and reducing vaccine-preventable disease.

In the U.S., minimum functional standards External Web Site Icon for the operation of immunization information systems were developed in 1997 by the Centers for Disease Control and Prevention, the National Vaccination Advisory Committee, and immunization program grantees

Summary of Task Force Recommendations and Findings

The Community Preventive Services Task Force recommends immunization information systems on the basis of strong evidence of effectiveness in increasing vaccination rates.

Evidence is considered strong based on the findings from 71 published papers and 123 conference abstracts showing that IIS are effective in increasing vaccination rates and reducing vaccine-preventable disease through their capabilities to:

  1. Create or support effective interventions such as client reminder and recall systems, provider assessment and feedback, and provider reminders
  2. Generate and evaluate public health responses to outbreaks of vaccine-preventable disease
  3. Facilitate vaccine management and accountability
  4. Determine client vaccination status for decisions made by clinicians, health departments, and schools
  5. Aid surveillance and investigations on vaccination rates, missed vaccination opportunities, invalid dose administration, and disparities in vaccination coverage

Task Force Finding and Rationale Statement

About the Interventions

  • In the U.S., most states and several cities have functioning IIS, with most systems consolidating records of vaccinations delivered to children up to 6 years of age (CDC).

Results from the Systematic Review

Evidence considered in this review included 194 papers (71 published papers and 123 conference abstracts) that represented both studies of IIS-supported interventions (e.g., client reminder and recall systems) and papers describing IIS program activities and experiences.

Studies were assigned to five categories for evidence assessment:

  • Overall evidence on effectiveness
    • One 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.
  • IIS-generated interventions to increase vaccination rates include
    • Client reminder and recall interventions:
      • Median absolute improvement in vaccination rates: 5 percentage points (interquartile interval: 3.6 to 6 percentage points; 10 studies, 13 study arms)
      • An additional 10 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- 15 percentage points; 5 studies)
      • An additional 7 descriptive studies reported the use of IIS to support the conduct of these interventions.
    • Provider reminder systems:
      • Absolute increase in vaccination rates: 14 percentage points (one study)
      • Many IIS in the U.S. have built-in reminders for vaccination providers when a client record is consulted.
  • IIS use in clinical decision support
    • No studies evaluated the use of IIS by vaccination providers at the clinic level.
    • Four studies described use of IIS in school settings.
    • Three studies described experiences among healthcare systems of adopting IIS as the primary data source for determination of vaccination rates at the clinic and system level.
  • IIS use in public health action
    • Twelve 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
    • 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.
    • Seven papers described the use of IIS in the process of vaccine supply management, distribution, and accountability; five involved doses distributed as part of the U.S. Vaccines for Children Program.
  • IIS use in public health decision support
    • The included papers described a range of IIS surveillance capabilities including:
      • Coverage assessments for specific vaccines (54 papers)
      • Investigations of vaccination rates among high risk subsets of the population (21 papers)
      • The ability to monitor the uptake of new vaccines (14 papers)

These reviews were conducted on behalf of the Task Force by a team of specialists in systematic review methods, and in research, practice and policy related to vaccinations to prevent diseases

Economic Review

The Task Force examined 12 studies providing information on costs and economic value of IIS as implemented and utilized in the U.S.

  • The information provided does not capture the full dimension of costs involved in the implementation and operation of IIS, and may be less relevant to current systems due to changes in technology, participation rates, and IIS functionality.
  • Available studies do not incorporate the full range of IIS operations, and may underestimate the true benefits provided by current, maturing systems.
  • Additional research is needed to update and address gaps in the available evidence, and enable a more comprehensive assessment of the economics of IIS.

Publication Status

Full peer-reviewed articles of this systematic review will be posted on the Community Guide website when published. Subscribe External Web Site Icon to be notified when we post these publications or other materials. See our library for previous Community Guide publications on this and other topics.



The findings and conclusions on this page are those of the Community Preventive Services Task Force and do not necessarily represent those of CDC. Task Force evidence-based recommendations are not mandates for compliance or spending. Instead, they provide information and options for decision makers and stakeholders to consider when determining which programs, services, and policies best meet the needs, preferences, available resources, and constraints of their constituents.

Sample Citation

The content of publications of the Guide to Community Preventive Services is in the public domain. Citation as to source, however, is appreciated. Sample citation: Guide to Community Preventive Services. Increasing appropriate vaccination: immunization information systems. Last updated: MM/DD/YYYY.

Review completed: July 2010