KEYWORDS:
Under-Immunization, Risk Factors, Racial Disparities, National Immunization Survey, Urban Areas

BACKGROUND:
Many factors, such as race, income, inter-state mobility and others, are known to influence vaccination coverage on a national level. Many cultural and sociological factors separate urban and non-urban areas. It is not known if these factors affect vaccine coverage differently in urban and non-urban settings.

OBJECTIVE(S):
To determine how risk factors associated with under-immunization differ in urban and non-urban areas.

METHOD(S):
The National Immunization Survey (NIS) is a large, ongoing, cross-sectional telephone survey of non-institutionalized civilians. We used the 1999 NIS data to compare rates of under-immunization for children living in urban and non-urban areas. We used logistic regression to assess risk factors associated with under-immunization, with completion of the 4:3:1:3:3 series.

RESULT(S):
In 1999, under-immunization rates for urban and non-urban areas were 30.5% and 25.8% respectively (p<.01). Income and race were not statistically significantly associated with under-immunization after controlling for other potential confounders in both urban and non-urban areas. Order of birth, mother’s age, and availability of shot card were associated with under-immunization in both urban and non-urban areas. Inter-state mobility was associated with increased under-immunization rates in urban areas but not in non-urban areas. Mother’s education, marital status, number and type of providers were associated with under-immunization in non-urban areas but not in urban areas.

CONCLUSIONS(S):
Under-immunization rates, and risk factors for under-immunization, are not the same in urban and non-urban areas. These differences should be considered when developing targeted interventions to increase vaccination coverage.

LEARNING OBJECTIVES:
1. Determine the risk factors that adversely affect immunization rates.
2. Compare the risk factors for under-immunization in urban and non-urban areas.