Objective: To identify factors associated with undervaccination at 3 months and 24 months among low-income, inner-city Latino and African-American preschool children.
Design: Interviews with a representative sample of inner-city families using a cross-sectional, multi-stage, cluster-sample design combined with a replicated quota sampling approach.
Setting: South Central and East Los Angeles areas in inner-city Los Angeles.
Population: Eight hundred seventeen Latino and 387 African-American families with children between 12 and 36 months of age.
Main outcome variables: Being fully immunized or up-to-date (UTD) at 3 months (1 diphtheria-tetanus-pertussis vaccine and 1 oral polio vaccine) and 24 months of age (4 diphtheria-tetanus-pertussis vaccines, 3 oral polio vaccines, and 1 measles-mumps-rubella vaccine).
Methods: Logistic regressions of UTD immunization status at 3 and 24 months by population and health care system factors.
Results: Seventy percent of Latino children and 53% of African-American children were UTD at 3 months of age. At 24 months of age, 42% of Latino children and 26% of African-American children were UTD on their immunizations. Receipt of the first immunizations by 3 months was associated with smaller family size, and evidence of connection to prenatal care. Latino children were less likely to be UTD at 24 months if they obtained well child care from private providers versus public clinics (odds ratio [OR] = 0.45, 95% confidence interval [CI] = 0.26, 0.79). There was also a trend for Latino children to be less well immunized if they were in health maintenance organizations versus public clinics (0.31, 0.05 < P < .1). African-American children were more likely to be UTD at 24 months if they were UTD at 3 months (OR = 5.56, 95% CI = 1.43, 21.6), had more health visits (OR = 1.13, 95% CI = 1.01, 1.27), and were less likely to be UTD at 24 months if they were on Medicaid versus private insurance (OR = 0.26, 95% CI = 0.08, 0.90).
Implications: Both African-American and Latino children in inner-city Los Angeles have low immunization rates at 3 and 24 months. Prenatal care and family size are strongly associated with being UTD by 3 months; however, family and child characteristics are relatively unimportant predictors of being UTD at 24 months of age. Important risk factors for underimmunization at 2 years of age in the inner-city, low-income communities studied include type of health insurance and source of well child care, with the public sector having higher rates than private doctors' offices or health maintenance organization/managed care plans.