BACKGROUND:
The National Immunization Survey (NIS) measures and monitors vaccination coverage among children aged 19-35 months in the U.S., the 50 states and 28 large urban areas.

OBJECTIVE:
To provide an overview of the NIS and trends in vaccination coverage estimates over time (1995-2002). Demonstrate disparities in coverage estimates by geography and selected socio-demographic characteristics. Describe public-use data files from the NIS that are released to facilitate additional analyses.

METHOD:
NIS consists of a random-digit-dialing telephone survey of the parents/guardians, followed by a mail survey of the children's providers. NIS collects vaccination histories from both households and providers. Only provider-reported histories are used to monitor vaccination coverage rates among young children. NIS is designed to produce vaccination coverage estimates for each of the recommended vaccines: diphtheria-tetanus toxoid-pertussis, poliovirus, measles-mumps-rubella or measles-containing vaccine, Haemophilus Influenzae type B, hepatitis B, varicella-zoster virus, pneumococcal vaccine, and selected combinations of these vaccines. Prior to release, contents of the public-use data files are carefully reviewed to reduce potential risk of disclosure of respondent's information.

RESULT:
NIS is a telephone survey with high response rates. In 2002, among 31,693 children with household interview data, 21,410 (67.6%) had vaccination histories from their providers. National estimates of vaccination coverage from the provider data were 77.5% for 4:3:1:3 and 74.8% for 4:3:1:3:3 series and vary substantially by geography and socio-demographic characteristics. Eight public-use data files have been released on the Internet (www.cdc.gov/nis ) and on CD-ROMs to facilitate additional analysis of the NIS data from 1995-2002.

CONCLUSION:
NIS is the only source of comparable estimates of vaccination coverage across all 50 states and 28 urban areas. Annual public-use data files are released to facilitate additional analyses by scientists, policy makers, and public health researchers.

LEARNING OBJECTIVES:
To demonstrate importance of the NIS as a tool to monitor and improve vaccination coverage rates in the U.S.