Australian influenza report 2010 - 18 - 24 September 2010 (#38/10)

The Australian Influenza Report is compiled from a number of data sources, including laboratory-confirmed notifications to NNDSS, sentinel influenza-like illness reporting from general practitioners and emergency departments, workplace absenteeism, and laboratory testing. A more in-depth annual report is also published in Communicable Diseases Intelligence.

Page last updated: 21 May 2010

Report No. 38
Week ending 18 - 24 September 2010

A print friendly version of this report is available as a PDF (300 KB)

The Department of Health and Ageing acknowledges the providers of the many sources of data used in this report and greatly appreciates their contribution.

Key Indicators

Influenza activity and severity in the community is monitored using the following indicators and surveillance systems:
Is the situation changing?Indicated by trends in:
  • laboratory confirmed cases reported to the National Notifiable Diseases Surveillance System;
  • GP Sentinel influenza-like illness (ILI) Surveillance;
  • emergency department (ED) presentations for ILI;
  • ILI-related absenteeism and call centre calls: and
  • sentinel laboratory test results.
How severe is the disease, and is severity changing?Indicated by trends in:
  • hospitalisations, ICU admissions and deaths from sentinel systems; and
  • clinical severity in hospitalised cases and ICU admissions.
Is the virus changing?Indicated by trends in:
  • drug resistance; and
  • genetic drift or shift from laboratory surveillance.

Summary

  • Levels of influenza-like illness (ILI) in the community have continued to increase through most surveillance systems this reporting period. Local, regional and widespread activity was reported within jurisdictions. The number of laboratory confirmed notifications has also increased.
  • There were 933 laboratory confirmed notifications of influenza during this reporting period, including 732 pandemic (H1N1) 2009 cases. Notifications of laboratory confirmed influenza were highest in SA.
  • Results from sentinel laboratory surveillance systems for this reporting period show that 17% of the respiratory tests conducted over this period were positive for influenza, which is a slight increase from the last reporting period (14%). In 2010, a total of 973 specimens have been positive for influenza
    (of 12,228 specimens tested), of which 69% were pandemic (H1N1) 2009, 9% were A/H3N2 and 19% were influenza B.
  • There have been 7,138 confirmed cases of influenza diagnosed in 2010 up to 24 September.
    A total of 41,715 confirmed cases of pandemic (H1N1) 2009 have occurred in Australia since May 2009.
  • Sentinel hospitals reported a decrease in the number of influenza associated hospitalisations compared to previous weeks, with 18 admissions during the reporting period, including 13 for pandemic (H1N1) 2009. ANZICS reported 12 ICU admissions for influenza and the APSU reported three cases of influenza complications in children (<15 years) this reporting period.
  • The WHO has advised that the world is no longer in phase 6 of influenza pandemic alert, and has moved into the post pandemic period. As at 1 August 2010, over 18,449 deaths worldwide have been reported associated with the pandemic virus. Chile has reported a recent increase in influenza notifications, most of which are H3N2.

1. Influenza activity in Australia

Geographic spread of influenza and ILI – Jurisdictional Surveillance

In the fortnight ending 17 September, influenza and ILI activity as reported by state and territory Health Departments indicated that there was ‘sporadic’ activity in TAS, ‘local’ activity in the ACT, ‘regional’ activity in NT and ‘widespread’ activity in SA, WA, QLD, VIC and NSW (Figure 1). Definitions of these activity levels are provided in the Data Considerations section of this report.

Figure 1. Map of influenza and ILI activity, by state and territory, during fortnight ending 17 September 2010
Figure 1. Map of influenza and ILI activity, by state and territory, during fortnight ending 17 September 2010
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Influenza-Like Illness

Sentinel General Practice Surveillance

In the week ending 19 September 2010, the national ILI consultation rate to sentinel GPs was approximately 12 cases per 1,000 consultations (Figure 2), a decrease from 26 cases per 1,000 consultations the previous week. The consultation rate is above levels seen at this time in 2009.

Figure 2. Weekly rate of ILI reported from GP ILI surveillance systems from 1 January 2007 to 19 September 2010*
Figure 2. Weekly rate of ILI reported from GP ILI surveillance systems from 1 January 2007 to 19 September 2010*

* Delays in the reporting of data may cause data to change retrospectively. As data from the VIDRL surveillance system is combined with ASPREN data for 2010, rates may not be directly comparable across 2007, 2008 and 2009.
SOURCE: ASPREN, and VIDRL GP surveillance system.



Of the ASPREN ILI specimens collected in the week ending 24 September 2010, 24% were positive for influenza, of which the majority were pandemic (H1N1) 2009 (13/20) (Table 1). Please note the results of ASPREN ILI laboratory respiratory viral tests do not currently include WA.

Table 1. ASPREN ILI consultations laboratory respiratory viral tests that were positive for influenza for the week ending 24 September 2010.
ASPREN – national
Total specimens tested85
Positive Influenza A13
Pandemic (H1N1) 20099
Seasonal A/H1N10
Seasonal A/H3N20
Influenza A untyped4
Positive Influenza B3
Positive – type unknown4

WA Emergency Departments

Respiratory viral presentations reported in WA EDs has decreased in the most recent week. An overall upward trend in ILI related ED presentations has occurred since the beginning of 2010 (Figure 3). In the week ending 19 September 2010 there were 521 respiratory viral presentations, including 26 admissions, a small decrease from 546 presentations in the previous reporting week.

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Figure 3. Number of respiratory viral presentations to WA EDs from 1 January 2007 to 19 September 2010 by week
Figure 3. Number of respiratory viral presentations to WA EDs from 1 January 2007 to 19 September 2010 by week

Source: WA ‘Virus Watch’ Report


NSW Emergency Departments

In the week ending 17 September 2010, ILI presentations to NSW EDs have remained low and stable at a rate of 1.6 per 1,000 presentations (Figure 4). ILI presentations were noted as being mainly for mild illness and there were no admissions to hospital during this period. In August 2010, there were 236 presentations with ILI, a rate of 1.7 per 1,000 presentations, with 19 admissions to hospital following presentation to EDs with ILI. This is similar to the previous month. The number of ILI presentations in 2010 continues to be well below seasonal levels observed in 2007-2009.

Figure 4: ILI presentations to NSW EDs from 2007-2010, by week
Figure 4: ILI presentations to NSW EDs from 2007-2010, by week
Source: NSW Health ‘Influenza Weekly Epidemiology Report'

Flutracking

Flutracking, a national online system for collecting data on ILI in the community, reported that in the week ending 26 September 2010, ILI activity levels appeared to decrease across Australia. Fever and cough were reported at equal rates for vaccinated and unvaccinated participants (2.9%) during this reporting period (Figure 5).

Figure 5. Rate of ILI symptoms among Flutracking participants by week, from week ending 30 May 2010 to week ending 26 September 2010
Figure 5. Rate of ILI symptoms among Flutracking participants by week, from week ending 30 May 2010 to week ending 26 September 2010

Source: Flutracking Interim Weekly Report


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National Health Call Centre Network

The number of calls to the National Health Call Centre Network (NHCCN) in this reporting period was slightly lower than in previous reporting periods (Figure 6), however the percentage of total calls remained stable.

Call numbers cannot be compared between early 2009 and early 2010, as not all call centres were online in early 2009. The difference in the number of operating call centres accounts for this apparent increase in recorded ILI calls (and baseline levels) between the two years.

Figure 6. Number of calls to the NHCCN related to ILI and percentage of total calls, Australia, 1 January 2009 to 24 September 2010
Figure 6. Number of calls to the NHCCN related to ILI and percentage of total calls, Australia, 1 January 2009 to 24 September 2010

Note: national data does not include QLD and VIC
Source: NHCCN data


Absenteeism

Due to system changes, absenteeism data has not been updated since July 2010. Absenteeism data will not be included in this report until provision of the data resumes.

Laboratory confirmed influenza

Sentinel Laboratory Surveillance

Results from sentinel laboratory surveillance systems for this reporting period show that 17% (125/727) of the respiratory tests conducted over this period were positive for influenza, which is a decrease from the last reporting period (14%) (Figure 7).

Figure 7. Total number of specimens tested by sentinel laboratories, and proportion positive, 1 January 2010 to 24 September 2010, by week
Figure 7. Total number of specimens tested by sentinel laboratories, and proportion positive, 1 January 2010 to 24 September 2010, by week

SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs



Sentinel laboratories reported 125 specimens positive for influenza during this reporting period, of which 86 were pandemic (H1N1) 2009, 3 were A/H3N2, 4 were influenza A (untyped) and 39 were influenza B (Table 2).

Table 2. Laboratory respiratory tests that tested positive for influenza, week ending 24 September 2010
NSW NICWA NICNT
(reported by WA NIC)
VIDRLTAS
Total specimens tested121409n/a13760
Positive Influenza A4583129
Pandemic (H1N1) 20094563106
Seasonal A/H1N100000
Seasonal A/H3N202010
Influenza A untyped00013
Positive Influenza B235101
In 2010, a total of 973 specimens have been positive for influenza (8% of 12,228 specimens tested), of which 69% were pandemic (H1N1) 2009, 9% were A/H3N2 and 19% were influenza B (Figure 8). Sentinel laboratory data are used in addition to National Notifiable Diseases Surveillance System (NNDSS) data to understand the strains circulating in Australia, as approximately 34% of NNDSS notifications are reported as influenza A untyped.

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Figure 8. Percentage of specimens tested by sentinel laboratories influenza positive, 1 January 2010 to 24 September 2010, by subtype
Figure 8. Percentage of specimens tested by sentinel laboratories influenza positive, 1 January 2010 to 24 September 2010, by subtype

SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs


Laboratory Confirmed Cases Notified to Health Departments

During this reporting period there were 933 influenza notifications reported to NNDSS (707 in SA, 138 in Qld, 31 in NT, 22 in WA, 19 in NSW, 9 in Vic, 4 in TAS and 3 in the ACT). They included 732 cases of pandemic (H1N1) 2009, 153 of influenza A (untyped), 1 of influenza A/H3N2, 43 of influenza B, and 4 untyped (see Figure 9).

There have been 7,138 confirmed cases of influenza of all types diagnosed during 2010 up to 24 September (Figure 9). Of these, 4,079 (57%) have been sub-typed as pandemic (H1N1) 2009 influenza, 2,408 (34%) as influenza A (untyped), 134 (2%) as A/H3N2 and 10 (<1%) as type A&B. A further 413 (6%) have been characterised as influenza type B, and 94 (1%) were untyped.

Figure 9. Laboratory confirmed cases of influenza in Australia, 1 January 2005 to 24 September 2010
Figure 9. Laboratory confirmed cases of influenza in Australia, 1 January 2005 to 24 September 2010

Source: NetEpi (2009; NSW 2010) and NNDSS (2010)
Note: The scale in this figure has been limited to 1600 notifications per week to allow for comparison
between 2010 and previous years. In 2009, notifications peaked at approximately 8,300 in Week 30.



In 2010 up to 24 September, the number of laboratory confirmed cases of influenza was 2,131 in SA, 1,767 in QLD, 1,223 in VIC, 851 in WA and 845 in NSW. There were a further 189 cases in the NT, 72 cases in the ACT and 60 cases in TAS (Figure 10). For a breakdown of trends by state and territory, see Figure 11.

Figure 10. Laboratory confirmed cases of influenza in Australia, 1 January to 24 September 2010, by state, by week.
Figure 10. Laboratory confirmed cases of influenza in Australia, 1 January to 24 September 2010, by state, by week.
Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: ACT

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: NSW

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: NT

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: QLD

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: SA

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: TAS

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: VIC

Figure 11. State breakdowns of laboratory confirmed cases on influenza, 1 January to 24 September 2010, by week: WA
In 2010, the distribution of influenza notifications has been relatively consistent across all age groups with an overall slight downward trend with increasing age. This distribution is reasonably similar to 2008 except in the 0-4 and the 74 and over age groups where sharp increases occurred in 2008 (Figure 12). In 2009 the distribution of influenza notifications tended to occur in persons aged less than 55 years, with substantially higher rates observed in persons aged less than 30 years, compared to older age groups.

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Figure 12. Laboratory confirmed cases of influenza (pandemic (H1N1) 2009 and seasonal) in Australia, 1 January 2008 to 24 September 2010, by age group
Figure 12. Laboratory confirmed cases of influenza (pandemic (H1N1) 2009 and seasonal) in Australia, 1 January 2008 to 24 September 2010, by age group

Source: NNDSS and NetEpi (NSW)

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2. Influenza severity to 3 September 20101

Pandemic (H1N1) 2009
While pandemic (H1N1) 2009 is generally considered a mild disease at the community level, it has had serious consequences for some people. Figures of hospitalisations, ICU admissions and deaths are currently used as indicators of the severity of the disease in Australia (Table 3).

Pandemic (H1N1) data for 2009 are currently being finalised through cleaning and validation processes. It is possible that these processes will result in some changes in the data presented here. Validated data will be progressively reported as these steps are completed.

Since the first case of pandemic (H1N1) 2009 in Australia in May 2009, there have been a total of 41,715 confirmed cases of pandemic (H1N1) 2009 in Australia as at 24 September 2010. Of these, 37,636 cases were reported in 2009 and 4,079 cases were reported in 2010. A total of 207 pandemic influenza-associated deaths have been reported, with 18 occurring in 2010.

Table 3. Summary of severity indicators of pandemic (H1N1) in Australia, 2009 and 2010 (up to 24 September 2010)
2009#2010a
Confirmed pandemic
(H1N1) 2009 cases
Hospitalised cases ICU casesDeaths Confirmed (H1N1) 2010 cases Deaths
Total number37,63613% (4,992/37,636) confirmed cases)14%
(681/4,992 hospitalisations)
191407918
Crude rate per 100,000 population172.122.83.10.918.6n/a
Median age (years)213144532252
Females51% (19,139/37,636) 51% (2,528/4,992)53%
(364/681)
44%50.7%
(2070/4079)
39%
(7/18)
Vulnerable groups (Indigenous persons, pregnant women & individuals with at least 1 co-morbidity)n/a58% (2,892/4,992)74%
(504/681)
67%n/a83%
(15/18)
Indigenous people~11% (3,877/34,750)20%
(808/4,048)
19%
(102/533)
13%7.4%
(116/1578)
0%
Pregnant women*n/a27%
(287/1,056 hospitalised females aged
15-44 years)
16%
(47/289) hospitalised pregnant women)
4% n/a0%
Cases with at least 1 co-morbidityn/a46% (2,303/4,992)67%
(457/681)
62%n/a83%
(15/18)
# Data are extracted from a number of sources depending on the availability of information. Figures used in the analysis have been provided in parentheses. Data are not always complete for each summarised figure.
a Data for 2009 from NetEpi, data for 2010 from NNDSS and NetEpi (NSW).
b The number of deaths is most likely under-reported and representative of hospital related death notifications only.
n/a - No data collected or available.
~ The denominator for this row is the number of confirmed cases for which Indigenous status is known. In 2010, 2501 cases had Indigenous status unknown. Includes women in the post-partum period.

1 Note that while the analysis of severity is on-going, updates are presented as required when there are significant changes detected. With the current low levels of pandemic (H1N1) 2009 influenza activity in Australia it is anticipated that the indicators of pandemic associated severity will not vary significantly.


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Influenza Hospitalisations

Influenza Complications Alert Network (FluCAN)

The Influenza Complications Alert Network (FluCAN) reported a decrease in the number of influenza associated hospitalisations in the week ending 24 September 2010, with 13 pandemic (H1N1) 2009 hospitalisations, two influenza A (not subtyped) hospitalisations and three influenza B hospitalisations from sentinel hospitals. For the period of 1 March to 24 September 2010, FluCAN has reported a total of 218 influenza associated hospitalisations (Figure 13). Of these hospitalisations, 176 have been associated with pandemic (H1N1) 2009, including 50 with ICU admission.

Figure 13. Number of influenza hospitalisations, sentinel hospitals, Australia, 1 March to 24 September 2010
Figure 13. Number of influenza hospitalisations, sentinel hospitals, Australia, 1 March to 24 September 2010

Source: Influenza Complications Alert Network (FluCAN). Data from 15 sentinel hospitals from all jurisdictions.



Table 4. FluCAN sentinel hospitalisation severity indicator summary 1 March to 24 September 2010
Pandemic (H1N1) 2009SeasonalTotal Influenza
All hospitalisedICU casesDeaths
All hospitalised ICU casesDeaths
All hospitalisedICU casesDeaths
ICU proportion of all hospitalised27%21%26%
Median age (years)35383639460353538
Females51% 46%66%59%44%0%53%45%66%
Total of vulnerable groups (Indigenous, pregnant & individuals with at least 1 co-morbidity)72%79%100%69%100%0%72%82%100%
Indigenous people5% 2%0%0%0%0%4%1%0%
Pregnant women8%15%0%7%11% 0%8%14%0%
% of all admission
% of women of child bearing age (15-49years)16%32%0%12%25%0%31%50%0%
Cases with at least 1 co-morbidity68%79%100%64%89%0%67%79% 100%
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Australian Paediatric Surveillance Unit (APSU)

A survey of admissions of children aged 15 years and under to Intensive Care Units (ICUs) around Australia following complications due to influenza infection is conducted through the Australian Paediatric Surveillance Unit (APSU). Details of admissions are reported on a weekly basis.

For the week ending 28 September 2010, there were three cases of severe influenza complication in children reported to the APSU. This is a decrease compared to the previous reporting week (4 cases) reported. Since 1 July 2010, 26 hospitalisations related to severe influenza complications have been reported in children aged 15 years and under. Twelve cases have been associated with pandemic (H1N1) 2009, of which four were admitted to ICU. Nine cases were associated with Influenza A (not further subtyped), and one case was associated with influenza B. Three of the cases associated with pandemic (H1N1) 2009 had an underlying chronic condition.

Intensive care admissions

The Australian and New Zealand Intensive Care Society (ANZICS) has reported a total of 149 ICU admissions for influenza in 2010, 12 of which occurred during this reporting period. Of these ICU admissions, 112 have been associated with pandemic (H1N1) 2009, 13 with influenza A (not subtyped), 2 with seasonal A/H3N2, 19 with seasonal H1N1 (these may be pandemic cases, yet to be confirmed) and 3 with influenza not typed (Figure 14).

Of the 112 pandemic (H1N1) 2009 ICU admissions in 2010, 86 had known co-morbidities and the median age at admission was 40 years (range 2-80).

Figure 14. Number of ICU admissions for influenza in Australia, 1 January to 24 September 2010
Figure 14. Number of ICU admissions for influenza in Australia, 1 January to 24 September 2010

Source: Australian and New Zealand Intensive Care Society (ANZICS) data base


Deaths associated with influenza and pneumonia

Nationally reported pandemic (H1N1) 2009 deaths

In 2010, 18 pandemic influenza related deaths have been notified to the NNDSS. The deaths occurred in late May, July, August and September, with a median age of 52 years. Sixteen of the deaths were reported as having underlying risk factors.

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NSW

Death registration data show that for the week ending 10 September 2010, there were 121 pneumonia or influenza associated deaths per 1,000 deaths in NSW, which is below the seasonal threshold for this period of 146 per 1,000 deaths (Figure 15).

NSW death registration data cross-matched with laboratory cases of influenza show 13 people with laboratory confirmed influenza have died up to 27 August 2010. All 13 cases had multiple comorbidities and were aged 50 years and over1

Figure 15. Rate of deaths classified as influenza and pneumonia from the NSW Registered Death Certificates, 2005 to 10 September 2010
Figure 15. Rate of deaths classified as influenza and pneumonia from the NSW Registered Death Certificates, 2005 to 10 September 2010
Source: NSW ‘Influenza Monthly Epidemiology Report'

3. Virology

Typing and antigenic characterisation - WHO Collaborating Centre for Reference & Research on Influenza (WHO CC) in Melbourne

From 1 January to 26 September 2010, there were 731 Australian influenza isolates subtyped by the WHO CC (Table 3).

Table 5. Typing of influenza isolates from the WHO Collaborating Centre, from 1 January 2010 to 26 September 2010
Type/SubtypeACTNSWNTQLDSATASVICWATOTAL
A(H1N1)000000000
Pandemic (H1N1) 2009163310513277119894656
A(H3N2)22050281635
B030250151540
Total1838105139823221125731

SOURCE: WHO CC
Please note: There may be up to a month delay on reporting of samples.
Isolates tested by the WHO CC are not necessarily a random sample of all those in the community, hence proportions of pandemic (H1N1) 2009 to seasonal are not representative of the proportions circulating.



Antigenic characterisation of 422ndemic (H1N1) 2009 isolates has shown 382 to be the A/California/7/2009-like strain and 4 a low reactor version of this strain. Antigenic characterisation of 27 type A/H3N2 isolates has shown 21 to be the A/Perth/16/2009-like and 6 to be the A/Perth/16/2009-like low reactor versions of the strain. One isolate was antigenically characterised as a low-reactor version of B/Florida/4/2006-like and 8 were characterised as B/Brisbane/60/2008-like.

Antiviral Resistance

The WHO Collaborating Centre in Melbourne has reported that from 1 January 2010 to 26 September 2010, no isolates (out of 443 tested) have shown resistance to oseltamivir or zanamivir by enzyme inhibition assay (EIA) and two pandemic (H1N1) 2009 isolates (out of 41 tested) have shown the H275Y mutation known to confer resistance to oseltamivir.

2011 Southern Hemisphere Vaccine

The WHO announced this week that the recommended vaccines for use in the 2011 influenza season (southern hemisphere winter) contain the following:
  • an A/California/7/2009 (H1N1)-like virus;
  • an A/Perth/16/2009 (H3N2)-like virus;
  • a B/Brisbane/60/2008-like virus2

4. International Influenza Surveillance

The WHO has advised that the world is no longer in phase 6 of influenza pandemic alert, and has moved into the post pandemic period.3 As of 1 August 2010 there have been over 18,449 deaths associated with pandemic (H1N1) 2009 influenza worldwide since April 20094.

Mexico has reported an increase in ILI and laboratory confirmed influenza notifications over the past two weeks. Of the laboratory confirmed samples, 98% were H3N2. This marks the beginning of a seasonal influenza period – six weeks earlier than expected5.

In New Zealand, the ILI consultation rate peaked in early August and has now returned to below baseline levels. Of the influenza viruses identified through sentinel and non-sentinel swab testing in the past week, 83% were pandemic (H1N1) 2009 influenza6

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5. Data considerations

The information in this report is reliant on the surveillance sources available to the Department of Health and Ageing. As access to sources increase and improve, this report will be refined and additional information will be included.

This report aims to increase awareness of pandemic (H1N1) 2009 and seasonal influenza in Australia by providing an analysis of the various surveillance data sources throughout Australia. While every care has been taken in preparing this report, the Commonwealth does not accept liability for any injury or loss or damage arising from the use of, or reliance upon, the content of the report. Delays in the reporting of data may cause data to change retrospectively. For further details about information contained in this report please contact the Influenza Team through flu@health.gov.au.

On 17 June 2009 Australia commenced the transition to a new response phase called PROTECT, in which laboratory testing is directed towards people with moderate or severe illness; those more vulnerable to severe illness; and those in institutional settings. This means that the number of confirmed cases does not reflect how many people in the community have acquired pandemic (H1N1) 2009 infection.

Geographic spread of influenza and ILI – Jurisdictional Surveillance

Jurisdictions report activity levels (in line with the definitions below) on a fortnightly basis, based on laboratory-confirmed notifications, various syndromic surveillance systems, outbreak reporting and rumour surveillance.
Activity levelDefinitions:
No activityNo influenza or ILI activity
Syndromic onlyan increase in syndromic surveillance systems with no laboratory confirmed cases
Sporadic small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak during the reporting period, but no increase in cases in syndromic surveillance systems
Local outbreaks of influenza or increases in cases in syndromic surveillance systems and recent laboratory-confirmed influenza in a single region of the state
Regional outbreaks of influenza or increases in cases in syndromic surveillance systems and a recent laboratory confirmed influenza in at least two but less than half the regions of the state
Widespreadoutbreaks of influenza or increases in cases in syndromic surveillance systems and recent laboratory-confirmed influenza in at least half the regions of the state.

Sentinel General Practice Surveillance

The Australian Sentinel Practices Research Network (ASPREN) has Sentinel GPs who report ILI presentation rates in NSW, NT, SA, ACT, VIC, QLD, TAS and WA. As jurisdictions joined ASPREN at different times and the number of GPs reporting has changed over time, the representativeness of ASPREN data in 2010 may be different from that of previous years. ASPREN data and VIDRL influenza surveillance data are sent to the Surveillance Branch on a weekly basis. Further information on Sentinel GPs’ Influenza Surveillance and ASPREN activities are available at www.dmac.adelaide.edu.au/aspren.

Sentinel ED data

WA - ED surveillance data are extracted from the ‘Virus Watch’ Report. This report is provided weekly. The Western Australia Influenza Surveillance Program collects data from eight Perth EDs. NSW - ED surveillance data are extracted from the ‘Weekly Influenza Report, NSW’. The New South Wales Influenza Surveillance Program collects data from 56 EDs across New South Wales.

FluTracking

FluTracking is a project of the University of Newcastle, the Hunter New England Area Health Service and the Hunter Medical Research Institute. FluTracking is an online health surveillance system to detect epidemics of influenza. It involves participants from around Australia completing a simple online weekly survey, which collects data on the rate of ILI symptoms in communities. Data have been provided weekly and have been presented in this report to show the pattern of self reported ILI in the community over the 2009 season.

Further information on FluTracking is available at www.flutracking.net/index.html.

National Health Call Centre Network

A national organisation provides call centre data for calls relating to ILI or influenza. Data are provided daily and are collated weekly and have been presented in this report to show the pattern of calls to this Call Centre over the 2009 and 2010 season. Data is available for all jurisdictions other than QLD and VIC.

Absenteeism

A national organisation provides data on the number of employees who have been on sick leave for a continuous period of more than three days. These data are not influenza or ILI specific and absenteeism may be a result of other illnesses.

Sentinel Laboratory Surveillance data

Laboratory testing data are provided weekly directly from PathWest (WA), VIDRL (VIC), ICPMR (NSW), sentinel Tasmanian laboratories, and ASPREN (national).

National Notifiable Diseases Surveillance System (NNDSS)

Laboratory confirmed influenza (all types) is notifiable in all jurisdictions in Australia. Confirmed cases of influenza are notified through NNDSS by all jurisdictions except NSW. NSW data are sourced from NetEpi.

NetEpi

In 2009, NetEpi, a web-based outbreak case reporting system for pandemic (H1N1) 2009, was used as the primary source of enhanced data on confirmed cases, hospitalisations and ICU admissions in all jurisdictions. In 2010, only data for NSW are sourced from NetEpi.

Analyses of Australian cases are based on the diagnosis date, which is the earliest of the onset date, specimen date or notification date.

Data Analysis

Analysis of confirmed influenza cases is conducted on combined NetEpi and NNDSS data. Analysis of morbidity (hospitalisations and ICU admissions) and mortality data in 2009 has been conducted on combined NetEpi and QLD hospitalisation data.

FluCAN

The Influenza Complications Network (FluCAN) collects detailed clinical information on all hospitalised cases of influenza and pneumonia from a sample of 15 sentinel hospitals across Australia. The data for this reporting period are sourced only from 14 hospitals.

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APSU

The Australian Paediatric Surveillance Unit collects clinical information on hospitalised cases of children aged 15 years and under with complications due to influenza infection. Approximately 1300 (80% of total) Paediatric clinicians registered with the Paediatrics and Child Health Division of the Royal College of Physicians, respond to APSU report cards. These report cards seek information regarding hospitalisations relating to 12 diseases or conditions, including influenza.

Australian and New Zealand Intensive Care Society data (ANZICS data)

The Australian and New Zealand Intensive Care Society provide data from a `near real time` registry of patients admitted to Australian ICUs. This documents the key factors influencing mortality, as well as the need for hospitalisation and mechanical ventilation. Information collected includes person characteristics and information on relevant co-morbidities, nature of the clinical syndrome associated with pandemic (H1N1) 2009, major therapeutic interventions from which organ failure outcomes can be imputed, vaccination status and vital status at time of ICU discharge and hospital discharge.

WHO Collaborating Centre for Reference & Research on Influenza (WHO CC)

Data are provided weekly to the Surveillance Branch from the WHO CC.

Deaths associated with influenza and pneumonia

Nationally reported pandemic (H1N1) 2009 deaths are notified by jurisdictions to the Commonwealth Department of Health and Ageing as they occur.

NSW influenza and pneumonia deaths data are collected from the NSW Registry of Births, Deaths and Marriages. Figure 14 is extracted from the ‘Weekly Influenza Report, NSW’.

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6. References

1 NSW Influenza Monthly Epidemiology Report, August 2010. Available from http://www.health.nsw.gov.au/publichealth/infectious/reports/influenza_report_august.asp Accessed 3 September 2010.
2 World Health Organisation Global Alert and Response: Influenza. Recommended composition of influenza virus vaccines for use in the 2011 southern hemisphere influenza season. Available from http://www.who.int/csr/disease/influenza/recommendations2011south/en/index.html Accessed 1 October 2010.
3 World Health Organisation virtual press conference, 10 August 2010. Available from http://www.who.int/en/ Accessed 11 August 2010.
4 WHO Influenza update – 10 September 2010. Available from http://www.who.int/csr/don/en/ Accessed 23 September 2010.
5 World Health Organisation Event Information for IHR National Focal Points, 29 September 2010.
6 New Zealand Weekly Influenza Update: 20-26 September 2010. Available from http://www.surv.esr.cri.nz/PDF_surveillance/Virology/FluWeekRpt/2010/FluWeekRpt201038.pdf Accessed 1 October 2010.