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Immunization Information System Progress --- United States, 2003

One of the national health objectives for 2010 is to increase to at least 95% the proportion of children aged <6 years who participate* in fully operational, population-based immunization registries (objective 14-26) (1). Immunization registries are confidential, computerized information systems that collect and consolidate vaccination data from multiple health-care providers, generate reminder and recall notifications, and assess vaccination coverage (2,3). A registry with added capabilities, such as vaccine management, adverse event reporting, lifespan vaccination histories, and interoperability with electronic medical records (EMRs), is called an immunization information system (IIS). This report summarizes data from CDC's 2003 Immunization Registry Annual Report (IRAR), a survey of IIS grantees in 50 states, five cities, and the District of Columbia (DC) that receive funding under section 317b of the Public Health Service Act. The findings of the 2003 IRAR indicate that approximately 44% of U.S. children aged <6 years participated in an IIS. In addition, 76% of public vaccination provider sites and 36% of private vaccination provider sites submitted immunization data to an IIS during the last 6 months of 2003. Increasing health-care provider participation by linking EMRs to IISs is vital to meeting the national health objective.

The 2003 IRAR, a self-administered, Internet-based questionnaire, was made available to immunization program managers as part of an annual reporting requirement. As in previous years, respondents were asked about the number of children aged <6 years participating in an IIS, health-care provider participation in the IIS, and other programmatic and technical functions (e.g., data linkages with other public health programs, data use, vaccine management, software/hardware capability, and reporting functions) (4). All 56 grantees were asked to complete the questionnaire; 52 reported on the number of children aged <6 years participating in an IIS. Estimates of the total number of children aged <6 years were based on 2003 U.S. Census data.

The findings indicated that, in 2003, approximately 44% of U.S. children aged <6 years participated in an IIS. Nine (16%) IIS grantees (Arkansas, Arizona, Delaware, DC, Michigan, New York City, North Dakota, Oregon, and San Antonio, Texas) had achieved the national health objective of >95% of children aged <6 years participating in an IIS (Figure). An additional eight (14%) grantees were approaching the national health objective, with participation of 81%--94%.

Nationally, 76% of public vaccination provider sites and 36% of private vaccination provider sites submitted immunization data to an IIS during the last 6 months of 2003.§ Twenty-five (45%) grantees reported that >95% of public provider sites submitted immunization data to an IIS; four (7%) reported submission of immunization data by 81%--94% of public provider sites. Five (9%) grantees (Arkansas, Connecticut, DC, Mississippi, and South Dakota) reported that >95% of private provider sites submitted immunization data to an IIS; six (11%) (Arizona, Hawaii, North Dakota, Oregon, Philadelphia, and Wisconsin) reported data submission by 81%--94% of private provider sites.

A substantial number of grantees reported linkages between an IIS and other information systems or entities. Twenty-two (39%) reported sharing data electronically with a Medicaid Management Information System. Thirty-six (64%) reported data linkages with the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Twenty-six (46%) reported IIS data access by health plans; 14 (25%) reported access by colleges and universities; 14 (25%) reported access by correctional facilities; 29 (52%) reported access by hospitals; and six (11%) reported access by long-term--care facilities. Nineteen (34%) reported that schools accessed an IIS to look up a student's vaccination status, and nine (16%) reported that schools had the ability to read, submit, and exchange data with an IIS.

Reported by: B Rasulnia, J Kelly, Immunization Svcs Div, National Immunization Program, CDC.

Editorial Note:

In 2003, approximately 44% of U.S. children aged <6 years participated in an IIS; the national health objective for 2010 is to increase this proportion to at least 95%. The findings presented in this report indicate that grantees must overcome substantial challenges to increase child and provider participation rates in IISs. CDC is developing a plan of action to identify and address the barriers to increasing child and provider participation.

Increasing data linkages between IISs and other health-information systems will enable consolidation of large immunization data sets, likely resulting in more complete immunization histories, increased coverage levels, improved support of outbreak containment, and decreased costs associated with over-immunization. Linkages have been developed between certain IISs and their respective state Medicaid Management Information Systems, blood-lead programs, and WIC programs. Such data linkages can improve program effectiveness and efficiency. For example, certain Medicaid programs use IIS data in Medicaid reports; some WIC programs use the IIS for patient look-up and subsequent referrals to immunization providers for children who are behind schedule; and many kindergartens and elementary schools access IIS data to obtain student immunization status. Protection of IIS data is managed through state privacy, confidentiality, and security laws and through compliance with federal privacy rules and regulations.

Current challenges to IIS linkages include a lack of data standards, which are essential for system interoperability (i.e., the ability to share data between software and hardware on disparate systems developed by different vendors). In 2001, to facilitate interoperability among health information systems, the CDC National Immunization Program (NIP) disseminated the Implementation Guide for Immunization Data Transactions using Version 2.3.1 of the Health Level Seven (HL7) Standard Protocol (5). The protocol is used by multiple IISs at local, state, and federal levels. In 2003, a total of 20 (36%) IISs reported the ability to process an HL7 immunization message and upload a patient record into an IIS consistent with the HL7 implementation guide. CDC, the Centers for Medicare and Medicaid Services, the Veterans Administration, and Indian Health Service have all adopted the IIS protocol standard, which allows for secure and confidential data sharing.

In 2003, the Consolidated Health Informatics (CHI) initiative adopted the IIS protocol standard for immunization data transactions. CHI is a federal initiative that adopts federal health-information--interoperability standards, thus enabling all federal health agencies to "speak the same language" (6). As national standards-development groups develop interoperability standards, the IIS community should be diligent in ensuring that the IIS protocol standard is part of these future standards.

The findings in this report are subject to at least two limitations. First, data from the 2003 IRAR are self-reported and might result in reporting bias. Second, because some grantees did not report data, the total participation of children aged <6 years might be an underestimate.

Linking EMRs to IISs is vital to increasing health-care--provider participation and meeting the national health objective for child enrollment in IISs. Monitoring the direction of EMR standardization at the national level needs to continue to ensure that IISs link with EMRs as a source of immunization data.


  1. US Department of Health and Human Services. Healthy people 2010 (conference ed, in 2 vols). Washington, DC: US Department of Health and Human Services; 2000. Available at
  2. National Vaccine Advisory Committee. Development of community and state-based immunization registries: report of the National Vaccine Advisory Committee (NVAC). Atlanta, GA: US Department of Health and Human Services, CDC; 1999. Available at
  3. Linkins RW. Immunization registries: progress and challenges in reaching the 2010 national objective. J Public Health Management Practice 2001;7:67--74.
  4. CDC. 2001 minimum functional standards for immunization registries. Atlanta, GA: US Department of Health and Human Services, CDC; 2001. Available at
  5. CDC. Implementation guide for immunization data transactions using version 2.3.1 of the Health Level Seven (HL7) standard protocol. Atlanta, GA: US Department of Health and Human Services, CDC; 2002. Available at
  6. Consolidated Health Informatics. Standards adoption recommendation: immunizations; 2003. Available at

* Participation is defined as having two or more vaccinations recorded in an immunization information system.

Paperless, clinical, encounter-based systems used by health-care providers and hospitals to manage patient medical histories.

§ Number of provider vaccination sites (public and private) is based on grantee self-reports.


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Date last reviewed: 7/27/2005


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