Pneumococcal disease is caused by Streptococcus pneumoniae (pneumococcus), a Gram-positive bacterium. Over 90 capsular antigenic types (serotypes) of this organism have been identified, but only a limited number cause the majority of pneumococcal disease.59,60 Pneumococci colonise the mucosal surface of the upper respiratory tract with no apparent symptoms in children and less commonly in adults (nasopharyngeal carriage).3,59 From the nasopharynx, pneumococci may spread locally to cause sinusitis or otitis media, or by inhalation into the lungs to cause pneumonia. Pneumococci can also enter the bloodstream to cause severe systemic disease such as bacteraemia, meningitis and, rarely, infection in remote sites such as joints, bones and soft tissues.3,61,62 Invasive pneumococcal disease (IPD) is the clinical condition in which Streptococcus pneumoniae is isolated from blood, cerebrospinal or pleural fluid, or other normally sterile sites. In the absence of a sterile site isolate, presumptive diagnosis of pneumococcal pneumonia is often made on the basis of isolation of the organism in sputum and/or other clinical or radiological features such as characteristic chest X-ray appearance.63 Acute otitis media is a much more common and less severe non-invasive manifestation of pneumococcal disease in children.64

Vaccination programs against pneumococcal disease in Australia over the years has addressed the increased pneumococcal disease burden among Aboriginal and Torres Strait Islander people.65 When funded pneumococcal vaccination programs using 23-valent polysaccharide vaccine (23vPPV) and the 7-valent conjugate vaccine (7vPCV) were introduced in Australia, they initially targeted only Aboriginal and Torres Strait Islander people.

Relevant vaccine history

1986

  • 23vPPV funded for children aged over 2 years with increased risk of pneumococcal disease or complications, due to specified underlying conditions, living in north Western Australia and the Northern Territory.

1991–1993

  • 23vPPV funded for all Aboriginal and Torres Strait Islander people aged over 2 years living in north Western Australia.

1995–1996

  • 23vPPV funded for Aboriginal and Torres Strait Islander people aged ≥50 years in the Northern Territory (1995) and Far North Queensland (1996, including people 15–49 years with underlying conditions).

1997

  • 23vPPV recommended for all Aboriginal and Torres Strait Islander adults aged >50 years.

1998

  • 23vPPV funded for Aboriginal and Torres Strait Islander adults aged >50 years and other adults aged >65 years in Victoria.

1999

  • 23vPPV funded nationally for all Aboriginal and Torres Strait Islander adults aged ≥50 years or aged 15–49 years with underlying conditions.

2000

  • 23vPPV eligibility in the Northern Territory changed to all Aboriginal and Torres Strait Islander people aged ≥15 years. 23vPPV eligibility in central Australia changed to all Aboriginal and Torres Strait Islander children aged 2–5 years.

2001

  • 7vPCV funded for all Aboriginal and Torres Strait Islander infants. A booster dose of 23vPPV was funded in the Northern Territory, Queensland, South Australia and Western Australia.

2005

  • 7vPCV funded for all children and 23vPPV funded for all adults aged ≥65 years.

2009

  • The Northern Territory replaced 7vPCV and 23vPPV in the routine childhood vaccination schedule with the 10vPCV.

2011

  • 13vPCV replaced all other pneumococcal vaccines for all children aged <2 years.

Key points

Substantial decreases in invasive disease and reductions in hospitalised pneumonia in some settings have been seen in Aboriginal and Torres Strait Islander children following 7vPCV vaccine introduction. No impact on otitis media has been reported. Impacts of vaccination on Aboriginal and Torres Strait Islander adults are less clear. Reducing vaccination delay in infants and improving coverage in adults are important to maximise the benefits of the existing vaccines.

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Disease trends

Notification data for IPD are complete from 2002. Over the 8-year period from January 2002 to December 2010, the rates of total IPD notifications (all ages reported from selected jurisdictions) remained much higher among Aboriginal and Torres Strait Islander people than among other people (Figure 2.9.1), with no clear overall trend. IPD notification rates for other people declined sharply from 2005 onwards, the year in which universal childhood pneumococcal conjugate vaccination and adult 23vPPV vaccination were introduced. Annual rates of total IPD notifications remained stable during 2008–2010 among both Aboriginal and Torres Strait Islander and other people.

Figure 2.9.1: Invasive pneumococcal disease notification rates and 95% confidence intervals, selected Australian states,* 2002 to 2010, by Indigenous status

Figure 2.9.1: is a line chart showing Invasive pneumococcal disease notification rates and 95% confidence intervals, selected Australian states, 2002 to 2010. A link to a text description follows.

* Jurisdictions with satisfactory data quality over the whole time period; see Appendix A (New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia).

† Notifications where the date of diagnosis was between 1 January 2002 and 31 December 2010. Rates are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2006.

Text description of Figure 2.9.1 (TXT 1 KB)

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In 2002–2004, there was initially a decline in the age-specific IPD notification rates in Aboriginal and Torres Strait Islander children in the 0–4 years age group, to almost equal the rates in other children in the same age group. But from 2005 onwards, IPD notification rates in Aboriginal and Torres Strait Islander children and other children diverged, with no clear trend in the former and a very steep decline in the latter (Figure 2.9.2). IPD notification rates in the ≥50 years age group also show contrasting trends between the two groups with an overall increase in Aboriginal and Torres Strait Islander people and a slow decline in other people. Among Aboriginal and Torres Strait Islander adults aged ≥50 years, there was a 58% increase in total IPD notifications from 2002 to 2010.

Figure 2.9.2: Invasive pneumococcal disease notification rates, selected Australian states,* 2002 to 2010, by age group and Indigenous status

Figure 2.9.2: is a line chart showing Invasive pneumococcal disease notification rates, selected Australian states, 2002 to 2010. A link to a text description follows.

* Jurisdictions with satisfactory data quality over the whole time period; see Appendix A (New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia).

† Notifications where the date of diagnosis was between 1 January 2002 and 31 December 2010.

Text description of Figure 2.9.2 (TXT 1 KB)

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Notification data are presented for all jurisdictions for the period 2007–2010. Hospitalisation data are presented for six jurisdictions (all except Tasmania and the Australian Capital Territory) by financial year for the period July 2005 to June 2010.

A total of 6,304 notifications of IPD were recorded during this reporting period, of which 698 (11%) were reported in Aboriginal and Torres Strait Islander people (Table 2.9.1). A total of 3,615 hospitalisations coded as pneumococcal meningitis or septicaemia (a proxy for IPD) were recorded during this reporting period, of which 397 (11%) were reported in Aboriginal and Torres Strait Islander people (Table 2.9.2).

The rates of notifications and the number of hospitalisations for IPD in both Aboriginal and Torres Strait Islander and other people were high in the 0–4 years and ≥50 years age groups and lowest in older children and young adults (Table 2.9.1 and Table 2.9.2). Among Aboriginal and Torres Strait Islander people, there was a marked rise in IPD rates from the 15–24 years to the 25–49 years age group, and the highest age-specific IPD notification rate was in the ≥50 years age group. The overall Indigenous to non-Indigenous rate ratios were 3.6:1 for notifications and 6.0:1 for hospitalisations, with the highest ratios (11.8:1 and 14.2:1, respectively) in the 25–49 years age group.

Table 2.9.1: Invasive pneumococcal disease notifications, all Australian states, 2007 to 2010, by age group and Indigenous status
Age group
(years)
Indigenous status Notifications* (2007–2010)
n Rate Rate ratio

* Notifications where the date of diagnosis was between 1 January 2007 and 31 December 2010.

† Average annual age-specific rate per 100,000 population.

‡ Includes cases with age unknown. Rates for all ages combined are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2006.

§ Indicates statistically significant, 95% confidence intervals do not overlap 1.0.

0–4
Indigenous
137
51.2
2.9§
Other
925
17.4
5–14
Indigenous
64
12.4
5.5§
Other
237
2.3
15–24
Indigenous
47
10.7
6.3§
Other
200
1.7
25–49
Indigenous
306
44.7
11.8§
Other
1,143
3.8
>50
Indigenous
144
53.3
4.6§
Other
3,100
11.6
All ages
Indigenous
698
42.0
3.6§
Other
5,606
11.5

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Table 2.9.2: Invasive pneumococcal disease hospitalisations, selected Australian states, 2005 to 2010, by age group and Indigenous status
Age group
(years)
Indigenous status Hospitalisations* (2005–2010)
n Rate Rate ratio

* Hospitalisations (New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia only) where the date of separation was between 1 July 2005 and 30 June 2010. The ICD-10-AM codes used to identify hospitalisations were G00.1 (pneumococcal meningitis) and A40.3 (pneumococcal septicaemia) (together considered to be a proxy for IPD).

† Average annual age-specific rate per 100,000 population.

‡ Includes cases with age unknown. Rates for all ages combined are age-standardised to the Australian Bureau of Statistics Australian population estimates for 2006.

§ Indicates statistically significant, 95% confidence intervals do not overlap 1.0.

0–4
Indigenous
83
26.5
3.7§
Other
436
7.1
5–14
Indigenous
32
5.2
5.2§
Other
124
1.0
15–24
Indigenous
15
3.0
4.3§
Other
97
0.7
25–49
Indigenous
195
24.5
14.2§
Other
613
1.7
>50
Indigenous
72
24.0
3.8§
Other
1,948
6.3
All ages
Indigenous
397
18.9
6.0§
Other
3,218
3.2

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The rates of hospitalisations coded as pneumococcal pneumonia (without codes for pneumococcal meningitis and septicaemia) show hospitalisation rates several-fold higher than for IPD in Aboriginal and Torres Strait Islander adults and the elderly, showing the substantially higher overall disease burden due to S. pneumoniae in this group (Figure 2.9.3).

Figure 2.9.3: Pneumococcal pneumonia (not coded as meningitis or septicaemia) hospitalisation rates, selected Australian states,* 2005 to 2010, by age group and Indigenous status

Figure 2.9.3: is a line chart showing  Pneumococcal pneumonia hospitalisation rates, selected Australian states, 2005 to 2010. A link to a text description follows.

* New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia.

† Hospitalisations where the date of separation was between 1 July 2005 and 30 June 2010. The ICD-10-AM code used to identify hospitalisations was J13 (pneumococcal pneumonia).

Text description of Figure 2.9.3 (TXT 1 KB)

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Serotype data were available for 93% (5,858) of the isolates from all IPD notifications. The notification rates of IPD caused by 7vPCV types declined in all age groups in the post-universal vaccination period (2006–2010) compared with the pre-universal vaccination period (2002–2004) in both Aboriginal and Torres Strait Islander and other people (Figure 2.9.4). This decline was most pronounced in the 0–4 years age group (87%). There was a concomitant increase in IPD caused by serotypes contained in 23vPPV but not in 7vPCV (23v-non-7) in all age groups, with the greatest fold increase seen in other children. The proportion of all IPD that was due to 7vPCV types in the 0–4 years age group in 2006–2010 was 6% in Aboriginal and Torres Strait Islander children and 9% in other children. In the same age group, the proportion of serotypes contained in the 13vPCV was significantly less among Aboriginal and Torres Strait Islander children (38%) than among other children (64%, P<0.0001). The main contributor to this difference was serotype 19A, which accounted for only 15% of all IPD in Aboriginal and Torres Strait Islander children but 46% in other children. However, the rate of serotype 19A in both groups of children was the same (8 per 100,000). Among adults ≥50 years of age, the proportion of disease caused by serotypes contained in the 23vPPV was similar (68% in Aboriginal and Torres Strait Islander people and 70% in other people).

Figure 2.9.4: Invasive pneumococcal disease notification rates for vaccine serotype groups, selected Australian states,* 2002–2004 compared with 2006–2010, by age group and Indigenous status

Figure 2.9.4: is a line chart showing Invasive pneumococcal disease notification rates for vaccine serotype groups, 2002-2004 compared with 2006-2010. A link to a text description follows.

* New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia.

Text description of Figure 2.9.4 (TXT 1 KB)

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There were 282 deaths reported to the Australian Bureau of Statistics from five jurisdictions (New South Wales, the Northern Territory, Queensland, South Australia and Western Australia) for the period 2006–2010 with IPD or ‘pneumococcal disease’ listed as the underlying or a contributing cause, of which 18–30 were reported in Aboriginal and Torres Strait Islander people (the ABS provides ranges when absolute numbers of deaths are low). ‘Pneumococcal disease’ was primarily the cause in adults (14/15–18), while IPD was more evenly distributed (1–4 each in <5 years, 5–49 years and ≥50 years age groups). Of the total 282 deaths, in 109 IPD (meningitis/septicaemia) or pneumococcal pneumonia was the underlying cause of death. There were 1–4 deaths reported in Aboriginal and Torres Strait Islander people with IPD as the underlying cause in each of the <5 years, 5–49 years and ≥50 years age groups, and 1–4 with pneumococcal pneumonia as the underlying cause in each of the 5–49 years and ≥50 years age groups.

In national notifications data for the same period and jurisdictions, there were 575 deaths reported as due to IPD, with 6% (n=34) of these in Aboriginal and Torres Strait Islander people. There were 30 deaths in children aged <5 years recorded in the national notifications data; of these, 5 (17%) were in Aboriginal and Torres Strait Islander children.

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Comment

The period covered by this report encompasses several years during which pneumococcal vaccination was publicly funded among Aboriginal and Torres Strait Islander as well as other children and adults. Therefore, the data presented here reflect the ongoing effects of those vaccination programs, predominantly using 7vPCV in children and 23vPPV in adults, on pneumococcal disease hospitalisations and notifications.

During this reporting period, sustained reductions in the notification rates for IPD caused by 7vPCV serotypes were seen among both Aboriginal and Torres Strait Islander and other people across all age groups, following the introduction of their respective childhood 7vPCV vaccination programs. The most dramatic decline in 7vPCV-type IPD was seen in other children. A rapid reduction in 7vPCV-type IPD was evident within a year of the introduction of universal vaccination, consequent to rapid achievement of high coverage. In comparison, there was a slower decline and a persistently higher IPD incidence in Aboriginal and Torres Strait Islander children. This is mainly due to the fact that the proportion of IPD caused by the 7vPCV types prior to vaccine introduction was lower in Aboriginal and Torres Strait Islander children than in other children.66-69

During the reporting period, the rates of total IPD hospitalisations and notifications were higher in Aboriginal and Torres Strait Islander people than in other people in all age groups. The Indigenous to non-Indigenous rate ratios continued to be lowest in those age groups directly targeted for vaccination where the greatest benefits were expected (i.e. 0–4 years and ≥50 years). Over the years, rates of IPD caused by 23v-non-7v types has increased to varying degrees in all age groups in both Aboriginal and Torres Strait Islander and other people. Serotype 19A was largely responsible for most of this serotype replacement disease among other children as in other developed countries.70-73 The increase in 19A was much less marked in Aboriginal and Torres Strait Islander children.74-76 It is possible but unproven that the childhood booster dose of 23vPPV was responsible for this effect. Among children in different population groups of Native Americans with similarly high levels of exposure to 7vPCV (without a 23vPPV booster) the changes in non-7v type disease varied considerably.77-79 Therefore there is not a consistent pattern of post-vaccination serotype changes in populations with high levels of pre-existing non-7vPCV IPD incidence. An outbreak of serotype 1 IPD that started in 2010 contributed to 23v-non-7v type disease increases in older Aboriginal and Torres Strait Islander children in central Australia.80

The rates of IPD in Aboriginal and Torres Strait Islander adults in the 25–49 years age group were 12–14 times the rates among other people in this age group for this reporting period, as they were in 2002–2005.13 This is partly a reflection of the greater disparity in the prevalence of risk factors associated with IPD, including smoking, chronic disease and heavy alcohol consumption, between Aboriginal and Torres Strait Islander and other people in this age group.81,82 The effectiveness of 23vPPV is limited among those with risk factors that include immunosuppression.83 There has been a remarkable decline in 7vPCV-type IPD in all adult age groups due to the indirect effect from the childhood vaccination program. However, the direct impact of 23vPPV in adults has been less clear in both Aboriginal and Torres Strait Islander and other people. Possible benefits of 23vPPV vaccination have been limited by vaccination coverage (from the few available data) being quite low in this age group.13 In Western Australian Aboriginal and Torres Strait Islander adults, the rate of IPD was higher in 2005–2007 than in 1997–2001, mainly due to 23v-non-7v types.69 Rates of all IPD and IPD due to 23v-non-7v types including 19A remained unchanged among Aboriginal and Torres Strait Islander adults in North Queensland and the Northern Territory, although there has been an increase in the range of non-vaccine serotypes causing IPD.75,76 As some of these serotypes are included in the 13vPCV, the indirect effect from 13vPCV use in children would be expected to result in some benefit to Aboriginal and Torres Strait Islander adults. The 13vPCV is now registered for use for adults ≥50 years of age, but it is not publicly funded and uptake is expected to be low. The results of ongoing large-scale studies of 13vPCV among adults will be vital for making policy decisions on providing public funding for 13vPCV for adults.

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Hospitalisations coded as pneumococcal pneumonia are a potential indicator of the burden of non-invasive pneumococcal infections, and changes in the rates of these hospitalisations may reflect the effect of pneumococcal vaccines on non-invasive disease.24 Several clinical trials have shown that pneumococcal conjugate vaccines are effective in preventing radiologically confirmed as well as clinically diagnosed pneumonia in children, although the greatest effect was on IPD in children.84,85 The hospitalisation rates for pneumococcal pneumonia were lower in this reporting period than in 2002–2005, with the reduction most pronounced in the 0–4 years age group for both the Aboriginal and Torres Strait Islander and other children.13 There has been a sustained reduction in hospitalisations coded as pneumonia in Aboriginal and Torres Strait Islander children <2 years of age in Western Australia, initially following targeted pneumococcal vaccination in these children and more pronounced after the introduction of the universal 7vPCV program.86,87 However, among Aboriginal and Torres Strait Islander children in the Northern Territory, 7vPCV and 23vPPV effectiveness assessments failed to demonstrate a significant effect against either hospitalisations for acute lower respiratory tract infections or radiologically confirmed pneumonia.88,89 Also, while there has been a reduction in the number of hospital procedures for otitis media in non-Indigenous children, no such impact has been detected for Aboriginal and Torres Strait Islander children.90,91 Lower serotype coverage of 7vPCV, greater diversity of pathogens, and suboptimal timeliness of vaccination in Aboriginal and Torres Strait Islander children may have limited the pneumococcal vaccine impact in these children.88,89,92,93 The higher valency vaccines (10vPCV and 13vPCV) that replaced 7vPCV may result in a greater effect on non-invasive as well as invasive disease.

There have been substantial overall reductions in IPD and some impact on pneumonia hospitalisations in Aboriginal and Torres Strait Islander children since the introduction of vaccination. Impacts in Aboriginal and Torres Strait Islander adults have been less obvious. Due to the wide serotype distribution of IPD in Aboriginal and Torres Strait Islander people, the six more serotypes covered by 13vPCV could provide considerable additional benefit to Aboriginal and Torres Strait Islander children and adults. This could include the prevention of serotype 1 outbreaks such as the one that occurred recently in Aboriginal and Torres Strait Islander people in central Australia. However, in the post-7vPCV era, the contribution of 13v-non-7v types to all IPD, and therefore the expected benefits from the 13vPCV, are much less in Aboriginal and Torres Strait Islander people than in other people, largely due to differences in distribution of serotype 19A. Pneumococcal conjugate vaccines with even broader serotype coverage or novel protein-based serotype-independent pneumococcal vaccines would be required to eliminate the continuing disparity between Aboriginal and Torres Strait Islander people and other people.94 It is important to continue surveillance of IPD in Aboriginal and Torres Strait Islander people to detect changes in serotype distribution and to match vaccines to disease-causing serotypes.