Vaccine-preventable disease (VPD) surveillance
VPD surveillance is carried out through analysis of de-identified national datasets of VPD notifications, hospitalisations and deaths. Notifications of VPDs collected through the National Notifiable Diseases Surveillance System are provided to NCIRS by the Communicable Diseases Network Australia, hospital separations due to VPDs are obtained from the National Hospital Morbidity Database and VPD deaths from the National Mortality Database are provided under a Research Associate Agreement with the Australian Institute of Health and Welfare.
Over and above analysis and reporting of notifiable disease data, where NCIRS collaborates extensively with the Australian Government Office of Health Protection and individual states and territories, NCIRS is the only organisation to systematically analyse hospitalisations coded as related to VPDs. Hospitalisations provide a valuable complimentary source of data, being generally a subset of more severe presentations compared with disease notifications. NCIRS has developed considerable expertise in assessing data quality and the relative merits and uses of hospitalisation versus notification data, which vary for each VPD. These issues are discussed in each biannual surveillance report, as well as in several peer-reviewed publications on data validity (see publications list).
Surveillance data are compiled in regular published national reports (see below), published epidemiologic reviews of particular VPDs (see publications list), as well as being included in reports for the Australian Technical Advisory Group on Immunisation and in national immunisation program evaluations.
National surveillance reports
NCIRS published the first national surveillance report on the epidemiology of vaccine preventable diseases and vaccination coverage in 2000, which reported on national data on notifications, hospitalisation and deaths attributable to selected important vaccine preventable diseases. The first report covered the period 1993–1998, and subsequent reports provided updates on these data every 2–3 years. Changes in the national immunisation schedules during the reporting periods were also described. The latest (fourth) report covered the period 2003–2005. It was published as a supplement issue of Communicable Diseases Intelligence in June 2007.
The fifth report is currently under preparation, and available national data from the most recent 2 years on notifications (2006 and 2007), hospitalisations (2005/2006 and 2006/2007) and deaths (2005 and 2006) will be reported. This report will also incorporate the second Annual Immunisation Coverage Report 2008.
Aboriginal and Torres Strait Islander people
NCIRS has also led the use of VPD surveillance data to evaluate and track trends in morbidity in Indigenous people. The reports on Vaccine Preventable Diseases and Vaccination Coverage in Aboriginal and Torres Strait Islander People have required development and/or application of new methods to determine the quality and completeness of Indigenous data. Establishing minimum criteria of data quality has identified improvements in some jurisdictions which have allowed wider use of data and subsequent publication through these reports. While the AIHW has developed methods for assessing data quality for hospitalisations in Indigenous people, NCIRS is the only organisation to systematically apply these standards to VPD hospitalisations.
Reports that focus on vaccine preventable diseases and vaccination coverage in Aboriginal and Torres Strait Islander people are published regularly. They are modelled on the national surveillance reports described above and provide a comparison of VPDs and vaccination coverage in Indigenous and non-Indigenous Australians. The quality of Indigenous health data is also a focus of these reports. The latest (second) report, which covered the period 2003–2006, was published as a supplement issue of Communicable Diseases Intelligence in June 2008.
