National Immunization Survey-IIS Study

Immunization Information Systems (IIS) have been increasingly used to monitor vaccine coverage, assess uptake of new vaccines, monitor vaccine use during shortages, and conduct other vaccine-related analyses. Completeness of the IIS data has been a primary concern in using the systems to routinely measure vaccination coverage. However, the best source of data on vaccinations among young U.S. children is still the National Immunization Survey (NIS). The NIS uses random-digit-dialing to find a sample of households with children 19-35 months of age. The NIS draws a separate sample for each calendar quarter and completes interviews with household respondents for about 32,000 children each year. With the consent of parents or guardians, the NIS also contacts the children's immunization providers (by mail) to request a complete vaccination history from the child's medical records.

In order to measure the data completeness of IIS and better understand how IIS data can add to the provider data collected from the NIS, CDC began the NIS-IIS Match Pretest in 2002. The pretest was conducted in two phases:

• Phase 1 included one quarter of data from Arizona, the District of Columbia, Michigan, and Oklahoma.
• Phase 2 began in 2004 and included two quarters of data from Mississippi, North Dakota, and South Dakota and one quarter of data from Wisconsin.

These IIS were chosen for the pretest because they have mature databases and over 75% of immunization providers participating. The goal was to explore using IIS to potentially reduce respondent burden on providers, lower the cost of the NIS, increase participation in and use of IIS, and improve the quality of efforts to monitor vaccination coverage. The pretest was a success, and the NIS-IIS Match Project has been conducted since 2008. In 2008, nine grantees participated in the NIS-IIS match project for children and results showed that agreement between NIS and IIS up-to-date status varied widely across grantees.

The NIS-Teen has been conducted since 2006 to assess adolescent vaccination-coverage based on provider-reported vaccination histories, and beginning in 2010, grantees were given the option of participating in the NIS-IIS Match for children and/or adolescents. It is important to continue to conduct this project and expand the number of grantees that participate to help answer questions that will improve both the NIS and the IIS.

The links below include results from the Pretest and from the 2008 NIS-IIS Match.

• Registry Data and the National Immunization Survey [268 KB, 16 pages]
  Authors: Lawrence Barker (CDC), Linda Piccinino (Abt Associates), Mike Battaglia (Abt Associates)
• Quality of vaccination histories reported from selected Immunization Information Systems (IIS): Results of the 2002 and 2004 NIS Experiments
  Authors: Meena Khare (CDC), James A. Singleton (CDC), Diana Bartlett (CDC)
• Comparison of Vaccination Coverage Estimates: NIS Versus IIS
  Authors: Kennon Copeland (NORC), Karen Wooten (CDC), Reiping Huang (NORC), Karen Cullen (CDC), Cynthia Howes (NORC)