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Immunization Registry Progress --- United States, January--December 2002

Immunization registries are confidential, computerized information systems that collect vaccination data within a geographic area (1). By consolidating vaccination records from multiple health-care providers, generating reminder and recall notifications, and assessing clinic and vaccination coverage, registries serve as key tools to increase and sustain high vaccination coverage (2). One of the national health objectives for 2010 is to increase to 95% the proportion of children aged <6 years who participate (i.e., have two or more vaccinations recorded) in fully operational, population-based immunization registries (objective 14.26) (3). This report summarizes data from CDC's 2002 Immunization Registry Annual Report (2002 IRAR), a survey of registry activity among immunization programs in the 50 states and the District of Columbia (DC) that receive grant funding under section 317b of the Public Health Service Act. These data indicate that approximately 43% of children aged <6 years are enrolled in a registry; achieving the national health objective will require increased implementation of functional standards to improve data quality.

The 2002 IRAR, a self-administered questionnaire, was distributed to immunization program managers as part of the annual reporting requirement. Respondents were asked about the number of children aged <6 years with two or more vaccinations recorded in an immunization registry and progress toward implementing the 12 functional standards considered essential for immunization registry operation (4).

A total of 37 (72%) states* reported operating registries that target their entire geographic areas. Seven (14%) other states (California, Georgia, Indiana, Massachusetts, Maryland, Minnesota, and New York) reported operating registries that target only regions or counties within their geographic areas, and the remaining seven (14%) states (Colorado, Kansas, Kentucky, Nebraska, New Mexico, Vermont, and Wyoming) reported no regional registry activity but were planning or piloting a statewide system. Nationwide, approximately 43% of U.S. children aged <6 years had two or more vaccinations recorded in a grantee registry. Four (8%) states (Arizona, Mississippi, North Dakota, and South Dakota) reported that >95% of children aged <6 years participated in an immunization registry (Figure). In the 44 states that operate registries regionally or statewide, an average of 75% of public vaccination providers and 31% of private providers submitted data to a registry during the last 6 months of 2002. Seven (16%) states (Arkansas, Connecticut, DC, Mississippi, North Dakota, Oregon, and South Dakota) reported that >75% of private vaccination providers submitted data to a registry.

All 51 immunization programs reported efforts to implement key elements of the 12 functional standards established for immunization registries (Table). Four (8%) states (Ohio, West Virginia, Wisconsin, and Wyoming) reported implementing all elements of the 12 functional standards. Seven (14%) other states (Alaska, Arkansas, Delaware, Idaho, Indiana, Louisiana, and Minnesota) implemented all elements of the functional standards except for exchanging data using the Health Level 7 (HL7) standard or establishing an immunization registry record within 6 weeks of birth.

Reported by: DL Bartlett, MPH, Immunization Svcs Div, National Immunization Program, CDC.

Editorial Note:

Immunization registries have made progress toward implementing the 12 immunization registry functional standards and enrolling more children and health-care providers in their systems. In 2002, only three functional standards (i.e., receive and process vaccination data within 30 days of vaccination, access information from the registry at the time of patient encounter, and produce reminder and recall notifications) reflected no increase in implementation at the state level, compared with six standards from the 2001 IRAR (5). In 2002, a total of 36 (71%) states included birth data in their registries, compared with 32 (63%) states in 2000 (6).

The findings in this report are subject to at least one limitation. Data from the 2002 IRAR are self-reported and might result in reporting bias, although site visits to certain immunization registries have shown high concordance with IRAR data (5).

Because 2002 IRAR data are self-reported by immunization program managers, efforts are under way to validate responses using data from the National Immunization Survey (NIS), a random-digit--dialed telephone survey of vaccine providers for children aged 19--35 months that estimates vaccination coverage for all 50 states and 28 urban areas (7,8). Although NIS focuses on a narrower age group, it can provide external validation to registry data and indicate areas for improving data quality. NIS also validates child participation in registries because it asks vaccine providers whether they submitted any child vaccination information to community or state immunization registries. In 2002, NIS data for 21,317 U.S. children, weighted to represent the U.S. population, indicated that 44% of children aged 19--35 months had their vaccination records reported to a community or state immunization registry, similar to the 43% reported in the 2002 IRAR for children aged <6 years.

NIS data also can be used to assess the completeness of registry data. Three months of 2002 NIS data were compared with data from four registries in three states and one city during the same period (9,10); the unweighted percentage of children with provider-verified NIS data who had two or more vaccinations logged in the registry ranged from 60% to 88% (9). In all cases, vaccination coverage estimates based on NIS provider-validated data were higher than registry-based data; approximately 40% of children had missing or incomplete registry information on doses of vaccine (10).

This level of data completeness indicates that registries need to improve data quality so that state and local health authorities can reliably calculate vaccination coverage and measure participation in immunization registries. Efforts are under way to develop additional tools to improve data quality; in 2002, CDC provided a tool to assess computer algorithms that prevent duplicate records in registry databases. For the 2002 IRAR, eight states and New York City reported performing this data quality test.

Registries also must improve functional and technical capacity to provide reliable evaluations and encourage data use by health-care providers and public health managers. In 2002, the National Immunization Program's Technical Working Group created Immunization Registry Certification guidelines for validating improvements to immunization registry functional standards and identifying registries with acceptable levels of technical capability. Additional information is available at; by telephone, 800-799-7062; or by e-mail,


  1. National Vaccine Advisory Committee. Development of community and state-based immunization registries: report of the National Vaccine Advisory Committee (NVAC). Atlanta, Georgia: U.S. Department of Health and Human Services, CDC, 1999. Available at
  2. Linkins RW. Immunization registries: progress and challenges in reaching the 2010 national objective. J Public Health Management Practice 2001;7:67--74.
  3. U.S. Department of Health and Human Services. Healthy People 2010, 2nd ed. With Understanding and Improving Health and Objectives for Improving Health (2 vols.). Washington, DC: U.S. Department of Health and Human Services, 2000.
  4. CDC. Immunization registry minimum functional standards. Available at
  5. CDC. Immunization registry progress---United States, 2002. MMWR 2002;51:760--2.
  6. CDC. Immunization registry use and progress---United States, 2001. MMWR 2002;51:53--6.
  7. Zell ER, Ezzati-Rice TM, Battaglia MP, Wright RA. National Immunization Survey: the methodology of an immunization surveillance system. Public Health Rep 2000;115:65--77.
  8. Smith PJ, Battaglia MP, Huggins VJ, et al. Overview of the sampling design and statistical methods used in the National Immunization Survey. Am J Prev Med 2001;40:17--24.
  9. Barker L. The National Immunization Survey/registry data comparison. Presented at the 2003 Immunization Registry Conference, Atlanta, Georgia, October 27--29, 2003.
  10. Khare M, Piccinino L, Battaglia MP, Linkins R. Immunization registries as supplemental sources of data for improving vaccination coverage estimates in the U.S. Presented at the 2003 Immunization Registry Conference, Atlanta, Georgia, October 27--29, 2003.

* For this report, DC is considered a state when summary data are presented.

Estimates of the number of children aged <6 years in the 50 states and DC are based on 2002 U.S. Census birth estimates.


Table 1
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Figure 1
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