KEYWORDS:
Vaccination coverage, telephone survey, random-digit-dialing

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 urban areas.

OBJECTIVE(S):
To present an overview of the NIS and demonstrate use of the public-use data files for producing estimates of vaccination coverage and conducting other analyses.

METHOD(S):
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 six recommended vaccines: diphtheria-tetanus toxoid-pertussis [DTP], poliovirus [Polio], measles-mumps-rubella [MMR] or measles-containing vaccine [MCV], Haemophilus Influenzae type B [Hib], hepatitis B [Hep B], varicella-zoster virus [VRC], and selected combinations of these vaccines, such as the 4:3:1:3 [4+ DTP/ 3+ polio/ 1+ MCV/ 3+ Hib] and 4:3:1:3:3 [4+ DTP/ 3+ polio/ 1+ MCV/ 3+ Hib/ 3+Hep B] series. Prior to release, contents of the public-use data files are carefully reviewed to reduce potential risk of disclosure of respondent’s information.

RESULT(S):
NIS is a telephone survey with high response rates. In 2001, among 33,437 children with household interview data, 70.4% had vaccination histories from their providers. Approximately 45.9% of the household-reported vaccination histories were obtained from written shot card records and the other 54.1% from memory recall. National estimates of vaccination coverage from provider data were 77.2% for 4:3:1:3 and 73.3% for 4:3:1:3:3 series. Seven public-use data files have been released on the Internet and CD-ROMs to produce coverage estimates and analyze annual NIS data for 1995-2001.

CONCLUSIONS(S):
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 provide an overview of the NIS and demonstrate the importance and use of provider-reported vaccination data to monitor and improve vaccination coverage in the U.S.