Announcement: Addition of Households with Only Cellular
Telephone Service to the National Immunization Survey, 2011
Before 2011, the National Immunization Survey (NIS) used a
random-digit–dialed, list-assisted landline telephone sample of
households to monitor national, state, and selected local area
vaccination coverage among noninstitutionalized children aged
19–35 months and 13–17 years (NIS-Teen) in the United States.
Since NIS was begun in 1994, landline telephone use has
decreased while cellular telephone use has increased. By the
second half of 2011, the proportion of children in the United
States living in households with only cellular telephone service
was 38.1% (1). At least one factor, poverty, has been associated
both with having only cellular telephone service and lower
vaccination coverage, increasing the potential for bias in
landline telephone surveys because of a lack of a representative
sampling frame (1–3). Beginning in 2011, the NIS sampling frame
was expanded from a single landline frame