The National Immunization Survey (NIS) was designed to measure vaccination
coverage estimates for the US, the 50 states, and selected urban areas for
children ages 19-35 months. The NIS includes a random-digit-dialed telephon
e survey and a provider record check study. Data are weighted to account fo
r the sample design and to reduce nonresponse and non-coverage biases in or
der to improve vaccination coverage estimates. Adjustments are made for bia
ses resulting from nonresponse and nontelephone households and estimation p
rocedures are used to reduce measurement bias,
The NIS coverage estimates represent all US children, not just children liv
ing in households with telephones. NIS estimates are highly comparable to v
accination estimates derived from the National Health Interview Survey.
The NIS allows comparisons between states and urban areas over time and is
used to evaluate current and new vaccination strategies.