Impact of North Carolina's universal vaccine purchase program by children's insurance status

Objective: To examine the impact of a new universal purchase vaccine program on immunization rates of children with different types of insurance. Design: Ecologic study using parent telephone interviews, medical chart abstraction in sites of outpatient care, and insurance verification with Medicaid and private insurers. Setting: State of North Carolina. Participants: Of a random birth certificate sample of 4385 children born in North Carolina during 1994 and 1995, 507 were excluded. A total of 2767 children had completed parent interviews; 95% of those had medical chart abstraction and insurance data. Main Outcome Measures: Immunization rates at each month during the first 2 years of age, site of delivery for immunizations and well-child visits, and insurance status. Results: In month-by-month comparisons, children born in 1995 had immunization rates 4% to 10% higher than their 1994 counterparts. By 24 months of age, 84% of the 1995 cohort had completed the primary immunization series, compared with 79% of the 1994 cohort (P<.001). In all insurance subgroups, 1995 immunization rates were higher than 1994 rates. The largest increases occurred among privately insured children with no well-child coverage, children who had periods of being uninsured, and children enrolled in Medicaid exclusively or with private insurance. More children in the 1995 cohort received immunizations in the private sector. Conclusions: Implementation of North Carolina's universal purchase program was associated with improved immunization rates, especially for children with inadequate insurance for well-child care. However, insurance status still influences the ability of children to receive immunizations on schedule.