Vaccine Preventable Diseases and Vaccination Coverage in Aboriginal and Torres Strait Islander People, Australia, 2003 to 2006

Vaccination coverage estimates from the National Aboriginal and Torres Strait Islander Health Survey and National Health Survey for Indigenous and non-Indigenous adults

Disclaimer: Produced by the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases and the Australian Institute of Health and Welfare on behalf of the Australian Government Department of Health and Ageing. Published as a supplement to the Communicable Diseases Intelligence journal Volume 32, June 2008.

Page last updated: 30 June 2008

The 2004–05 NATSIHS and NHS also provide data on coverage for the influenza and pneumococcal vaccines in adults, as well as the presence of high-risk medical conditions which are indications for vaccination in younger adults.

Prevalence of risk factors for which influenza and/or pneumococcal vaccination were recommended in Aboriginal and Torres Strait Islander adults aged less than 50 years

As the recommendations for influenza and pneumococcal vaccination for Indigenous adults aged 15–49 years are based on the presence of risk factors, data on the prevalence of those risk factors in Indigenous Australians are relevant for interpreting vaccination coverage in this population.

Risk factors for which the influenza vaccine is recommended include at least one of many chronic medical conditions, including severe asthma. In 2004–2005, approximately 17% of Aboriginal and Torres Strait Islander Australians aged 18–49 years reported at least one of the chronic medical conditions (listed in Appendix C (II)) that were considered risk factors of influenza for which vaccination was recommended. Diabetes mellitus, chronic cardiovascular, respiratory and kidney conditions predominated. The proportion of this population with at least one risk factor rose to 29% when current asthma was included.

Risk factors for which the pneumococcal vaccine is recommended include at least one of many chronic medical conditions (but not including asthma), heavy alcohol use and tobacco smoking. In 2004–2005, the proportion of Aboriginal and Torres Strait Islander Australians aged 18–49 years who reported at least one chronic medical condition (as listed in Appendix C (I)) or heavy alcohol use was 32%, and rose to about 66% when tobacco smoking was added.

There was a gender difference in reported prevalence of risk factors that are indications for influenza vaccine in Aboriginal and Torres Strait Islander Australians aged 18–49 years, with lower rates in males compared with females for chronic conditions including asthma (21% and 36%, respectively). However, there was no gender difference for the risk factor indications for pneumococcal vaccine, which includes smoking (66% for both genders).

When comparing remote and non-remote areas, while the prevalence of a risk factor for which the influenza vaccine was recommended was not significantly different between Aboriginal and Torres Strait Islander residents of remote and non-remote areas (26% and 30%, respectively), a higher prevalence was reported in residents of remote areas who had a risk factor for which the pneumococcal vaccine was recommended (71% for remote residents compared with 64% for non-remote residents). There was no significant difference in prevalence of these risk factors among various jurisdictions of residence (see Tables E5 and E6 in Appendix E).

The prevalence of risk factors generally increased with age, although this trend was more marked for risk factors that were indications for influenza vaccine than for pneumococcal vaccine (Figure 20).

Figure 20. Percentage of Aboriginal and Torres Strait Islander persons aged 18 years or more who had risk factors for contracting influenza or pneumococcal disease reported in 2004–2005, by age group, Australia

Figure 20. Percentage of Aboriginal and Torres Strait Islander persons aged 18 years or more who had risk factors for contracting influenza or pneumococcal disease reported in 2004–2005, by age group, Australia

Source: Australian Bureau of Statistics National Aboriginal and Torres Strait Islander Health Survey, 2004–05.

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Coverage of influenza and pneumococcal vaccination in Aboriginal and Torres Strait Islander adults

Coverage of influenza and pneumococcal vaccinations by age groups

Vaccination coverage in various age and risk groups, in both Indigenous and non-Indigenous adults, are shown for influenza vaccine in Figure 21 and pneumococcal vaccine in Figure 22.

Figure 21. Percentage of population who reported having influenza vaccination in the last 12 months prior to survey in 2004–2005, by Indigenous status and age group, Australia

Figure 21. Percentage of population who reported having influenza vaccination in the last 12 months prior to survey in 2004–2005, by Indigenous status and age group, Australia

* Chronic disease or asthma.

Source: Australian Bureau of Statistics National Aboriginal and Torres Strait Islander Health Survey, 2004–05.

Figure 22. Percentage of population who reported having pneumococcal vaccination in the last five years prior to survey in 2004–2005, by Indigenous status and age group, Australia

Figure 22. Percentage of population who reported having pneumococcal vaccination in the last five years prior to survey in 2004–2005, by Indigenous status and age group, Australia

* Chronic disease, heavy alcohol use or smoking.

Source: Australian Bureau of Statistics, National Aboriginal and Torres Strait Islander Health Survey, and National Health Survey, 2004–05.

While the percentage of people who were fully vaccinated for influenza was consistently higher than that for pneumococcal vaccine, for both vaccines a similar pattern was seen between the age and risk groups represented.

In Aboriginal and Torres Strait Islander adults, the lowest coverage was in younger adults (15–49 years) with no statistically significant difference in coverage between those for whom the vaccine was recommended (with risk factors) and those for whom it was not recommended (without risk factors). In older Aboriginal and Torres Strait Islander adults, all of whom were recommended to be vaccinated, the coverage was higher. Coverage was highest in the oldest age group (65 years or more), for which vaccination was also recommended and funded for non-Indigenous adults. In the age group for which vaccination was only recommended and funded for Aboriginal and Torres Strait Islander adults (50–64 years), coverage was significantly lower.

There were no significant differences in coverage between genders in the categories shown in these figures (data not shown).

Coverage was significantly higher in Indigenous compared with non-Indigenous adults in their respective age groups, with the exception of pneumococcal vaccine in those age 65 years or more. It should be noted that pneumococcal vaccine was funded for non-Indigenous adults in that age group for only part of the period covered by the survey.

Vaccination coverage by jurisdiction by remoteness and risk factor category is presented in Tables E5 to E8 in Appendix E.

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Increase in uptake of influenza and pneumococcal vaccination over time

Among Aboriginal and Torres Strait Islander adults aged 50 years or more, for whom the influenza and pneumococcal vaccines were universally recommended, vaccine uptake increased from 2001 to 2004–2005 for both vaccines, although the increases did not reach statistical significance (Figure 23).

Figure 23. Vaccination coverage of Aboriginal and Torres Strait Islander adults aged ≥50 years, 2004–2005 compared with 2001, by vaccine

Figure 23. Vaccination coverage of Aboriginal and Torres Strait Islander adults aged ≥50 years, 2004–2005 compared with 2001, by vaccine

Source: Australian Bureau of Statistics, National Health Survey 2001 Indigenous supplemental survey, and National Aboriginal and Torres Strait Islander Health Survey, 2004–05.

Differential uptake of influenza and pneumococcal vaccinations by remoteness of residence

A significantly higher uptake of both vaccines was observed in Aboriginal and Torres Strait Islander adults aged 50 years or more living in remote areas compared with non-remote areas (Figure 24). A similar pattern was seen in younger adults for both vaccines, and older adults (65 years or more) for pneumococcal vaccine, but there was no statistically significant difference in influenza coverage by remoteness for older adults (data not shown).

Figure 24. Vaccination coverage of Aboriginal and Torres Strait Islander adults aged ≥50 years, by remoteness of residence and vaccine, 2004–2005

Figure 24. Vaccination coverage of Aboriginal and Torres Strait Islander adults aged ≥50 years, by remoteness of residence and vaccine, 2004–2005

Source: Australian Bureau of Statistics National Aboriginal and Torres Strait Islander Health Survey, 2004–05.

Variation in uptake of influenza and pneumococcal vaccinations among Australian states and territories

For both influenza and pneumococcal vaccines, there was substantial variation in vaccination coverage between jurisdictions in Aboriginal and Torres Strait Islander adults. Data for those aged 18–49 years who had at least one relevant risk factor are presented in Figure 25, and more detailed data on that age group in Tables E5 and E6 in Appendix E. The highest coverage was reported in the Northern Territory for both vaccines, where the pneumococcal vaccine (but not the influenza vaccine) was recommended for all Aboriginal and Torres Strait Islander adults.

Figure 25. Percentage of Aboriginal and Torres Strait Islander persons aged 18–49 years with at least one relevant risk factor who had vaccination prior to survey in 2004–2005, by jurisdiction of residence, Australia

Figure 25. Percentage of Aboriginal and Torres Strait Islander persons aged 18–49 years with at least one relevant risk factor who had vaccination prior to survey in 2004–2005, by jurisdiction of residence, Australia

Source: Australian Bureau of Statistics National Aboriginal and Torres Strait Islander Health Survey, 2004–05.

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Comment

This report is the broadest in scope and most detailed presentation of vaccination coverage data on Aboriginal and Torres Strait Islander people yet published. This has been made possible by improvements in ACIR data quality and the increased sample size of the NATSIHS compared with previous surveys.

For vaccines recommended for all children, coverage in Indigenous children at age 12 months was between 2% and 9% lower than in non-Indigenous infants nationally. This discrepancy disappeared by age 24 months, suggesting that delayed vaccination was more common in Aboriginal and Torres Strait Islander infants, who eventually caught up with the recommended doses by 24 months. At 5 years of age, fewer children had received all the recommended vaccines, but there was no disparity between Indigenous and non-Indigenous children at the national level. This pattern was not uniform across all jurisdictions, with coverage in Aboriginal and Torres Strait Islander children lower than the national average in some, while in others coverage was actually higher. This improved data quality now provides the opportunity for the ACIR to be used to assist providers and program managers to identify regions where increased attention is required to improve coverage in Aboriginal and Torres Strait Islander children.

For vaccines recommended only for Aboriginal and Torres Strait Islander people, coverage was consistently and substantially lower than for the universal vaccines. This may be partly due to under-reporting of these vaccines to the ACIR, but the same phenomenon has been reported in surveys, of adults (reported here) and children.18 This demonstrates the greater difficulty in delivering these targeted programs, to all ages, and the need for improved systems to deliver them. While lower coverage was found in non-remote areas in Aboriginal and Torres Strait Islander adults, and previously in children,35 more recent analyses of ACIR data do not find this to be the case for universal vaccines with higher coverage.17 The low coverage for hepatitis A and 23vPPV in Aboriginal and Torres Strait Islander children in this report, vaccines which are only recommended in the north and west of Australia, demonstrates that difficulties in achieving high coverage are not limited to urbanised areas.

Among Aboriginal and Torres Strait Islander adults, it is generally observed that the coverage is higher with the influenza vaccine than the pneumococcal vaccine in most ages, jurisdictions and remoteness strata. This may be partly explained by the limitations in the self-reporting methods used in data as discussed in the Methods section, yet the scale of the difference suggests it is likely that there is some true difference between the uptake of these two vaccines.

In younger Aboriginal and Torres Strait Islander adults with a risk-factor-based program, vaccination was not delivered to a high proportion of eligible people. The substantially higher coverage in older adults is very suggestive of the superiority of an age-based program over an age-and-risk-based vaccination program.

In fact, the Australian Technical Advisory Group on Immunisation (ATAGI) has recently recommended annual influenza vaccination for all Aboriginal and Torres Strait Islander adults,57 although this recommendation is not yet publicly funded.