Kate Pennington and the Enhanced Invasive Pneumococcal Disease Surveillance Working Group,for the Communicable Diseases Network Australia

Summary

The number of notified cases of invasive pneumococcal disease (IPD) in the first quarter of 2017 was less than the previous quarter, but greater than the number of notified cases in the first quarter of 2016. Overall, the decline in disease due to the serotypes targeted by the 13-valent pneumococcal conjugate vaccine (13vPCV) has been maintained across all age groups since the 13vPCV replaced the 7-valent pneumococcal conjugate vaccine (7vPCV) in the childhood immunisation program from July 2011 (Figure 1).

Figure 1: Notifications of invasive pneumococcal disease, Australia, 1 January 2002 to 31 March 2017, by vaccine serotype group, year and quarter

Text version of the Figure (TXT 1 KB)

^#1999 - 23vPPV funded for all Indigenous Australians aged 50 years and over, as well as younger Indigenous Australian adults with risk factors.
^*NIP - National Immunisation Program.

Key points

In the first quarter of 2017, there were 247 cases of IPD reported to the National Notifiable Disease Surveillance System (NNDSS). This represented a 38% decrease compared to the fourth quarter of 2016 (n=395) and a 35% increase when compared with the same period in 2016 (n=183) (Table 3). In the first quarter of 2017 the most common pneumococcal serotypes causing IPD were 3 (11%), 19F (7%), 22F (6%) and 23B (6%) (Table 2).

In non-Indigenous Australians this quarter, the number of notified cases was highest in children aged less than 5 years and older adult age groups, especially those aged 60 years or older (Table 3). In Indigenous Australians, cases were highest in children aged less than 5 years, and the 40-44 and 50-54 years age groups. The proportion of cases reported as Indigenous Australians this quarter (11%; 28/247) was lower compared to the proportion observed in the previous quarter (18%; 45/395), and similar compared to the proportion reported in the first quarter of 2016 (11%; 26/183).

In children aged less than 5 years, there were 46 cases of IPD reported, representing 19% of all cases reported in this quarter. The proportion of cases notified in this age group was higher in this reporting period when compared with the previous quarter (14%; 54/395), and similar compared to the proportion reported in the first quarter of 2016 (19%; 34/183). Of those cases with a known serotype reported this quarter, 33% (11/33) were due to a serotype included in the 13vPCV compared with 56% (23/41) of cases in the previous and 35% (9/26) in the first quarter of 2016 (Figure 2). During this quarter there were a number of different serotypes affecting this age group with no clear dominance (Table 2). Serotypes 3, 19A and 23B continued to be the common serotypes reported amongst this age group.

Figure 2: Notifications and annual rates* of invasive pneumococcal disease in children aged less than 5 years, Australia, 1 January 2007 to 31 March 2017, by vaccine serotype group

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* Annual rates are shown on quarter 2, excluding 2017.

In the first quarter of 2017, there were four cases reported in fully vaccinated children aged less than 5 years who were considered to be 13vPCV failures. These 13vPCV failures were due to serotypes 19A (n=2) and 19F (n=2) (Table 4).

Among Indigenous Australians aged 50 years and over, there were 10 cases of IPD reported this quarter. Of those cases with a reported serotype (n=9), only two were due to a serotype included in the 23-valent pneumococcal polysaccharide vaccine (23vPPV) and overall there was no particular serotype dominant (Figure 3). The number of notified cases of IPD in this age group were less than the number of cases reported in both the previous quarter (n=14) and the first quarter of 2016 (n=12).

Among non-Indigenous Australians aged 65 years and over there were 80 cases of IPD reported this quarter. The number of notified cases of IPD in this age group decreased by 43% when compared to the previous quarter (n=142) but was 40% higher than the number reported in the first quarter of 2016 (n=57). Of those cases with a reported serotype, 61% (46/76) were due to a serotype included in the 23vPPV (Figure 4), which was similar to the proportion in the previous quarter (63%; 86/137). For this quarter, serotypes 3 (n=9), 11A (n=7) and 19F (n=7) were the most common serotypes for this population group, noting that these three serotypes are included in the 23vPPV.

Figure 3: Notifications and annual rates* of all invasive pneumococcal disease in Indigenous Australians aged 50 years or over, Australia, 1 January 2007 to 31 March 2017, by vaccine serotype group

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^*Annual rates are shown on quarter 2, excluding 2017.

Figure 4: Notifications and annual rates^* of all invasive pneumococcal disease in non-indigenous Australians^# aged 65 years or over, Australia, 1 January 2007 to 31 March 2017, by vaccine serotype group

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^* Annual rates are shown on quarter 2, excluding 2017.
^# Non-Indigenous Australians includes cases reported with as non-Indigenous, not stated, blank or unknown.

During this quarter there were 19 deaths attributed to a variety of IPD serotypes, with serotype 3 (n=5) predominant. Almost all of the reported deaths (18/19) occurred in non-Indigenous Australians^*. The median age of those cases who died was 78 years (range 1 to 96 years).

Notes

The data in this report are provisional and subject to change as laboratory results and additional case information become available. More detailed data analysis of IPD in Australia and surveillance methodology are described in the IPD annual report series published in Communicable Diseases Intelligence.

In Australia, pneumococcal vaccination is recommended as part of routine immunisation for children, individuals with specific underlying conditions associated with increased risk of IPD and older Australians. More information on the scheduling of the pneumococcal vaccination can be found on the Immunise Australia Program website (www.immunise.health.gov.au).

In this report, a ‘vaccine failure’ is reported when a child aged less than 5 years is diagnosed with IPD due to a serotype found in the 13vPCV and they have received 3 primary scheduled doses of 13vPCV at least 2 weeks prior to disease onset with at least 28 days between doses of vaccine.

There are 3 pneumococcal vaccines available in Australia, each targeting multiple serotypes (Table 5). Note that in this report serotype analysis is generally grouped according to vaccine composition.

Follow-up of all notified cases of IPD is undertaken in all states and territories except New South Wales and Victoria who conduct targeted follow-up of notified cases aged under 5 years, and 50 years or over for enhanced data. Follow-up of notified cases of IPD in Queensland is undertaken in all areas except Metro South and Gold Coast Public Health Units who conduct targeted follow-up of notified cases for those aged under 5 years only. However, in these areas where targeted case follow-up is undertaken, some enhanced data may also be available outside these targeted age groups.

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^* Non-Indigenous Australians includes cases reported with as non-Indigenous, not stated, blank or unknown.

Acknowledgements

Report prepared with the assistance of Mr Mark Trungove and Ms Rachael Corvisy on behalf of the Enhanced Invasive Pneumococcal Disease Surveillance Working Group.

Enhanced Invasive Pneumococcal Disease Surveillance Working Group contributors to this report include (in alphabetical order): Frank Beard (NCIRS), Heather Cook (NT and secretariat), Lucinda Franklin (Vic.), Carolien Giele (WA), Robin Gilmour (NSW), Michelle Harlock (Tas.), Ben Howden (Microbiological Diagnostic Unit, University of Melbourne), Sanjay Jayasinghe (NCIRS), Vicki Krause (Chair), Shahin Oftadeh (Centre for Infectious Diseases and Microbiology Laboratory Services, NSW Health Pathology), Sue Reid (ACT), Vitali Sintchenko (Centre for Infectious Diseases and Microbiology- Public Health, Westmead Hospital), Helen Smith (Queensland Health Forensic and Scientific Services), Janet Strachan (Vic.), Hannah Vogt (SA), Angela Wakefield (Qld).

Author details

Corresponding author: Kate Pennington, Communicable Disease Epidemiology and Surveillance Section , Office of Health Protection, Australian Government Department of Health, GPO Box 9484, MDP 14, Canberra, ACT 2601. Telephone: +61 2 6289 2725. Facsimile: +61 2 6289 1070. Email: cdess@health.gov.au

Table 1: Notified cases of invasive pneumococcal disease, Australia, 1 January to 31 March 2017, by Indigenous status, serotype completeness and state or territory

Table 1-This table shows the numbers of IPD cases which have occurred during the first quarter of 2017 for each state and territory by Indigenous status and serotype completeness compared to historically relevant periods. The number of cases in this quarter was less than the previous quarter, but more than the equivalent quarter in 2016. Data on Indigenous status was complete for 87% of cases in all states and territories, with slightly higher levels of completeness in those aged groups targeted for follow-up by all jurisdictions. Serotype completeness overall this quarter continued to be high at almost 90%.

Indigenous status	ACT	NSW	NT	Qld	SA	Tas	Vic	WA	Total 1st qtr 2017	Total 4th qtr 2016	Total 1st qtr 2016	Year to date 2017
Indigenous	0	8	4	6	2	0	1	7	28	45	26	28
Non-Indigenous	2	59	1	35	25	7	37	20	186	308	144	186
Not stated / Unknown	0	12	0	0	0	0	20	1	33	42	13	33
Total	2	79	5	41	27	7	58	28	247	395	183	247
Indigenous status completeness* (%)	100	85	100	100	100	100	66	96	87	89	93	87
Indigenous status completeness in targeted groups *† (%)	100	87	100	100	100	100	90	94	93	96	99	93
Serotype completeness ‡ (%)	100	90	100	98	52	86	98	93	89	93	92	89
* Indigenous status completeness is defined as the reporting of a known Indigenous status, excluding the reporting of not stated or unknown Indigenous status. † Targeted groups for followup by almost all jurisdictions and public health units are cases aged less than 5 years and 50 years and over. ‡ Serotype completeness is the proportion of all cases of invasive pneumococcal disease that were reported with a serotype or reported as non-typable. Incomplete serotype data can occur in cases when (i) no isolate was available as diagnosis was by polymerase chain reaction and no molecular typing was attempted or was not possible due to insufficient genetic material; (ii) the isolate was not referred to the reference laboratory or was not viable; (iii) typing was pending at the time of reporting, or no serotype was reported by the notifying jurisdiction to the National Notifiable Diseases Surveillance System.

Table 2: Distribution of serotypes causing invasive pneumococcal disease in notified cases, Australia, 1 January to 31 March 2017, by age group

Table 2- This table shows the distribution of serotypes by age group over the reporting quarter, including a reference to any relevant vaccine type. It shows that serotype 3 was the most common cause of IPD this quarter followed by serotypes 19A and 22F.

Serotype	Vaccine type	Age groups			Serotype total
		Under 5 years	5-64 years	Over 65 years
3	13vPCV non-7vPCV	4	13	9	26
19F	7vPCV	3	8	7	18
22F	23vPPV non-13vPCV	2	8	5	15
23B	Non-vaccine type	4	6	4	14
19A	13vPCV non-7vPCV	4	5	3	12
9N	23vPPV non-13vPCV	-	9	2	11
11A	23vPPV non-13vPCV	-	2	7	9
23A	Non-vaccine type	1	4	4	9
15A	Non-vaccine type	3	1	4	8
7F	13vPCV non-7vPCV	-	8	-	8
8	23vPPV non-13vPCV	-	6	2	8
15B	23vPPV non-13vPCV	4	1	1	6
16F	Non-vaccine type	-	4	2	6
33F	23vPPV non-13vPCV	-	5	1	6
6C	Non-vaccine type	1	2	3	6
10A	23vPPV non-13vPCV	1	1	3	5
12F	23vPPV non-13vPCV	1	2	2	5
15C	Non-vaccine type	2	2	1	5
35B	Non-vaccine type	-	2	3	5
Other	-	3	21	15	39
Unknown	-	13	9	4	26
Total		46	119	82	247
* Serotypes that only occur in less than 5 cases per quarter are grouped as ‘Other’ and include ‘non-typable’ isolates this quarter. † ‘Serotype unknown’ includes those serotypes reported as ‘no isolate’, ‘not referred’, ‘not viable’, ‘typing pending’ and ‘untyped’.

Table 3: Notified cases of invasive pneumococcal disease, Australia, 1 January to 31 March 2017, by Indigenous status and age group

Table 3: This table shows the number of IPD cases by Indigenous status and age group for the quarter. In the current reporting quarter, 11% of IPD cases were reported as Indigenous, 75% of cases were reported as non-Indigenous and 14% did not have Indigenous status reported.

Age group	Indigenous status			Total
	Indigenous	Non-Indigenous	Not reported*
00-04	4	40	2	46
05-09	0	4	1	5
10-14	1	1	0	2
15-19	1	1	1	3
20-24	1	3	1	5
25-29	1	2	3	6
30-34	3	4	2	9
35-39	1	8	1	10
40-44	5	3	5	13
45-49	1	6	6	13
50-54	6	13	0	19
55-59	1	12	0	13
60-64	1	17	3	21
65-69	0	10	1	11
70-74	1	15	3	19
75-79	1	20	1	22
80-84	0	5	1	6
85+	0	22	2	24
Total	28	186	33	247
* Not reported is defined as not stated, blank or unknown Indigenous status.

Table 4: Characteristics of 13vPCV failures in children aged less than 5 years, Australia, 1 January to 31 March 2017

Table 4: This table shows the characteristics of 13vPCV failures in children aged less than 5 years for the current reporting quarter. Four cases were reported in fully vaccinated children aged less than 5 years who were considered to be 13vPCV failures. Serotypes 19A and 19F were the serotypes associated with 13vPCV failures reported this quarter.

Age	Indigenous status	Serotype	Clinical category	Risk factor/s
2 years	Non-Indigenous	19A	Pneumonia	Other
3 years	Non-Indigenous	19F	Pneumonia	No risk factor identified
3 years	Non-Indigenous	19F	Pneumonia	Childcare attendee
3 years	Non-Indigenous	19A	Bacteraemia	Childcare attendee

Table 5: Streptococcus pneumoniae serotypes targeted by pneumococcal vaccines

Table 5: This table shows the four pneumococcal vaccines available in Australia and the multiple serotypes targeted by each vaccine. The 7-valent pneumococcal conjugate vaccine (7vPCV) targets serotypes 4, 6B, 9V, 14, 18C, 19F and 23F. The 10-valent pneumococcal conjugate vaccine (10-vPCV) targets the same serotypes as the 7vPCV plus 1, 5 and 7F. The 13-valent pneumococcal conjugate vaccine (13-vPCV) targets the same serotypes as the 10vPCV plus 3, 6A and 19F. The 23-valent pneumococcal polysaccharide vaccine (23-vPPV) targets same serotypes as the 10vPCV plus 2, 3, 8, 9N, 10A, 11A, 12F, 15B, 17F, 19A, 20, 22F and 33F.

Serotypes	7-valent pneumococcal conjugate vaccine (7vPCV)	10-valent pneumococcal conjugate vaccine (10vPCV)	13-valent pneumococcal conjugate vaccine (13vPCV)	23-valent pneumococcal polysaccharide vaccine (23vPPV)
1		✓	✓	✓
2				✓
3			✓	✓
4	✓	✓	✓	✓
5		✓	✓	✓
6A			✓
6B	✓	✓	✓	✓
7F		✓	✓	✓
8				✓
9N				✓
9V	✓	✓	✓	✓
10A				✓
11A				✓
12F				✓
14	✓	✓	✓	✓
15B				✓
17F				✓
18C	✓	✓	✓	✓
19A			✓	✓
19F	✓	✓	✓	✓
20				✓
22F				✓
23F	✓	✓	✓	✓
33F				✓