BACKGROUND: All children receiving Medicaid in Rhode Island, except the disabled and those in foster care, must enroll in a participating managed care plan and designate a specific primary care provider who is responsible for providing a broad range of health services with an emphasis on prevention.

OBJECTIVE: To assess the immunization status of children enrolled in a hospital-based Medicaid managed care practice.

METHODS: We examined the medical records of all children between the ages of 19 and 35 months who had been continuously enrolled in the Medicaid managed care practice at Rhode Island Hospital for the last six months of 1996. All 594 children meeting this criteria were included in the study sample regardless of their frequency of visits. Immunization status was determined for the following vaccines: DTP (4 doses), HIB (4 doses or one after 15 months), polio (3 doses), hepatitis B (3 doses), MMR (1 dose) and overall for the basic series. Two strategies were used in determining the immunization status of the study children: (1) a simple count of all documented vaccines (“Count”), and (2) only including vaccines that met minimal age and spacing intervals based on AAP and CDC recommendations (“Strict”).

RESULTS: Immunization status of study children, shown below, are expressed as percent up to date. Early administration of the fourth dose of DTP and the second dose of hepatitis B had a major influence on lowering the measured immunization rates for these vaccines using the “Strict” assessment method.

CONCLUSIONS: If minimal intervals of administration are not taken into account, vaccine specific immunization rates approach national goals in this multi-ethnic, low income group. However, overall coverage and rates derived from the “Strict” method of assessment are considerably lower. The data demonstrate the importance of considering the issue of the timing of vaccine administration when interpreting immunization rates. These findings have implications for provider education and indicate the importance of having policies for re-vaccinating children who were immunized at shortened intervals. Table

Table 1 No caption available.