Measuring vaccine coverage

Why do we measure vaccine coverage? First, measuring vaccine coverage allows us to determine whether the immunisation program we have in place is working, that is, are children actually being vaccinated. Second, a measure of coverage allows us to establish if enough children are being vaccinated so that transmission of diseases will be interrupted. Finally, calculation of coverage at a local level allows us to identify specific areas of low coverage so that measures to improve coverage can be appropriately targeted. 

Detailed exploration and monitoring of vaccine coverage data is critical to underpin efforts to achieve and maintain high coverage in children, adolescents and adults. NCIRS plays a preeminent role in the analysis and reporting of data from the Australian Immunisation Register (AIR) and the use of these data for research, surveillance and program evaluation. NCIRS downloads de-identified data from the AIR every 3 months.

Australian Immunisation Register

The AIR is administered by the Australian Government Department of Human Services, which also administers Medicare. It has 3 main functions: 

  • to record vaccines given, both on the National Immunisation Program Schedule and privately, to people of all ages in Australia from birth to death

  • to provide immunisation status information to parents and providers

  • to provide a tool for monitoring vaccine coverage by age, vaccine, Aboriginal and Torres Strait Islander status and region.

The register was initially established as the Australian Childhood Immunisation Register (ACIR) on 1 January 1996, and included all children under the age of 7 years enrolled in Medicare. Participation in the ACIR was opt-out, so it constituted a nearly complete population register, as approximately 99% of children are registered with Medicare by 12 months of age. Since 2001, immunisations given overseas may be recorded if a provider endorses their validity. From 30 September 2016, the ACIR became the AIR, recording vaccinations given to people of all ages. 

Measuring vaccine coverage using the AIR 

Vaccine coverage is usually expressed as the proportion or prevalence (%) of complete immunisation by particular assessment ages. Coverage data are usually provided for each major vaccine type and for all vaccines due at a number of age milestones. In Australia, childhood immunisation aged milestones are set at:

  • 12 months (for vaccines due at 6 months)

  • 24 months (for vaccines due at 12 and 18 months)

  • 60 months (for vaccines due at 4 years).

A set number of vaccine types and doses are due at each of these milestones. A detailed description of the methods used for calculating coverage at the population level can be found in our latest national annual immunisation coverage report.

In 2017, NCIRS, with support from the Australian Government Department of Human Services and state and territory health departments, undertook a national study to assess the effectiveness of data transfer to AIR and identify ways to improve it. This study represents the first attempt at the national level since 2001 to systematically audit the accuracy of AIR data. The study was funded by the Australian Government Department of Health.

Annual immunisation coverage reports, Australia

NCIRS produces annual national immunisation coverage reports to highlight important trends and issues in vaccine coverage in Australia. These reports provide a detailed summary of vaccine coverage at standard milestone ages, coverage for vaccines not included in standard coverage assessments, timeliness of vaccination, vaccine coverage for Aboriginal and Torres Strait Islander children, small area vaccine coverage data, and adolescent vaccine coverage.

Latest report - 2017 Annual immunisation coverage report can be viewed here.
2016 Annual immunisation coverage report

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Previous reports

Annual Immunisation coverage reports for Australia since 2007 can be accessed here.

Annual immunisation coverage reports, New South Wales

NCIRS also produces annual immunisation coverage reports for New South Wales. These can be accessed here.

AIR data transfer study

The AIR data transfer study is the first attempt at the national level since 2001 to systematically audit the accuracy of AIR data. In 2016 the Australian Government Department of Health (Health) funded NCIRS to undertake, with support from the Australian Government Department of Human Services (DHS) and state and territory health departments, a national study to assess the effectiveness of data transfer to AIR and identify ways to improve it. On the basis of our findings, the most influential areas in which data recording, transfer and handling could be improved to optimise the effectiveness of data transfer to AIR include:

  1. data entry for all methods of transfer to AIR

  2. processes for transfer of vaccination encounter information to AIR

  3. data management to reduce duplicate records

  4. engagement with and enhancing support to immunisation providers.

2018 AIR data transfer study

Vaccine coverage estimates 

The latest vaccine coverage estimates calculated from the AIR are available here.

Last updated December 2018