Initially the records of all children under seven years of age registered with Medicare at 19th January 1996 were copied onto a database file and each was allocated a personal identification number. Subsequently, any child under seven years of age who was not registered with Medicare but for whom notification of an immunisation encounter is received by the HIC are added to the ACIR and assigned a temporary number. Some of these children may later be registered following enrolment with Medicare. Using these data, it is the responsibility of the HIC to provide routine coverage reports, and administer a recall-reminder system. It is the HIC's responsibility to provide routine coverage reports.
Coverage is calculated using a cohort-type method.
Immunisation coverage rates by state are shown below. These indicators allow the assessment of the internal validity of the ACIR in each quarter and improve the reliability of calculation of coverage rates on a quarterly basis. These include indicators that measure duplication, indicators that calculate the amount of missing information, indicators that measure the accuracy of information on the ACIR and indicators that calculate the timeliness of information. A report on the data quality indicators was drafted and presented to the ACIR Management Committee in late March 1998 with a favourable response. The ACIR data has provided an opportunity to develop exploratory models of good and poor immunisation coverage.