Immunization status of children enrolled in a hospital-based medicaid managed care practice: the importance of the timing of vaccine administration.
OBJECTIVE
To evaluate the immunization status of children enrolled in a hospital-based Medicaid managed care practice and to assess the impact of the timing of vaccine administration on measured immunization rates.


METHODS
The medical records of all children between the ages of 19 and 35 months who were continuously enrolled in the Medicaid managed care practice for the last 6 months of 1996 were reviewed. Immunization status was determined for the following vaccines: diphtheria-tetanus-pertussis/diphtheria-tetanus-acellular pertussis (4 doses); Haemophilus influenzae type b (3 doses); poliovirus (3 doses); hepatitis B (3 doses); measles-mumps-rubella (1 dose); and overall for the basic series. Two assessment methods were used to determine the immunization status of the study children: (1) a count of all documented vaccines ("count"); and (2) only including vaccines that met minimal age and spacing intervals based on American Academy of Pediatrics and CDC recommendations ("interval assessment").


RESULTS
With the count method vaccine-specific immunization rates ranged from 88 to 95%, with overall coverage of 80% for the basic series. With the interval assessment method vaccine-specific immunization rates ranged from 74 to 92%, with overall coverage of 53% for the basic series.


CONCLUSIONS
When all documented vaccines were included in the assessment, vaccine-specific immunization rates approached national goals, although overall coverage remained below 90% in this Medicaid managed care practice. The substantially lower immunization rates obtained by the interval assessment method demonstrate the importance of considering the issue of vaccine timing when interpreting immunization rates and the need for policies for revaccinating children who were immunized at less than recommended intervals. The results also have implications for provider education regarding the early administration of vaccines.
Vivier
P M
PM
Department of Pediatrics, Brown University, Providence, RI, USA. Patrick_Vivier@Brown.edu
Alario
A J
AJ
Simon
P
P
Flanagan
P
P
O'Haire
C
C
Peter
G
G
D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D018073:Haemophilus Vaccines / Q000008:administration & dosage; D017325:Hepatitis B Vaccines / Q000008:administration & dosage; D006785:Hospitals, University; D006801:Humans; D007114:Immunization / Q000706:statistics & numerical data*; D007115:Immunization Schedule; D007223:Infant; D008329:Managed Care Programs; D008458:Measles Vaccine / Q000008:administration & dosage; D022542:Measles-Mumps-Rubella Vaccine; D008484:Medicaid; D009108:Mumps Vaccine / Q000008:administration & dosage; D011054:Poliovirus Vaccine, Inactivated / Q000008:administration & dosage; D012411:Rubella Vaccine / Q000008:administration & dosage; D013997:Time Factors; D014481:United States; D017778:Vaccines, Combined / Q000008:administration & dosage
D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; D017325:Hepatitis B Vaccines; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine; D011054:Poliovirus Vaccine, Inactivated; D012411:Rubella Vaccine; D017778:Vaccines, Combined