Report No. 28A print friendly version of this report is available as a PDF (227 KB)
Week ending 16 July 2010
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 IndicatorsInfluenza activity and severity in the community is monitored using the following indicators and surveillance systems:
|Is the situation changing?||Indicated by trends in:
|How severe is the disease, and is severity changing?||Indicated by trends in:
|Is the virus changing?||Indicated by trends in:
- Levels of influenza-like illness (ILI) in the community are continuing to show signs of increasing through some surveillance systems (ASPREN, WA Emergency Departments and NHCCN calls).
- Reporting from sentinel laboratories suggests that influenza activity is increasing, with 5% of tests positive for influenza. The most common respiratory viruses diagnosed by sentinel laboratories this reporting period were respiratory syncytial virus (RSV) in WA and NSW and picornavirus in VIC.
- In 2010, sentinel laboratories reported that 144 specimens have been positive for influenza (of 6445 specimens tested), of which 62% were pandemic (H1N1) 2009, 28% were A/H3N2, 6% were influenza B and 4% were influenza A (untyped).
- Of the 1,362 confirmed cases of influenza of all types diagnosed during 2010 up to 16 July, there have been 212 confirmed cases of pandemic (H1N1) 2009 influenza reported in Australia, bringing the total of confirmed cases to 37,848 since May 2009. There have been 17 new confirmed cases of pandemic (H1N1) 2009 influenza diagnosed and reported in Australia (Qld, NT, SA and WA) during this reporting period.
- Sentinel hospitals have reported four hospitalisations for influenza in this reporting period, including three for pandemic (H1N1) 2009. ANZICS reported no ICU admissions for influenza during this period.
- In China, influenza B accounted for 53.5% of influenza viruses detected in the week to 4 July 2010. Of these, approximately 50.8% are the same strain as that in the 2010 Southern Hemisphere vaccine.
- As at 12 July 2010, the WHO Regional Offices have reported over 18,337 deaths associated with pandemic (H1N1) 2009 influenza worldwide. Current pandemic influenza transmission remains low.
1. Influenza activity in Australia
Geographic spread of influenza and ILI – Jurisdictional SurveillanceIn the fortnight ending 9 July 2010, influenza and ILI activity as reported by state and territory Health Departments indicated that there was ‘sporadic’ activity in five states (ACT, NSW, VIC, QLD and SA), ‘local’ activity in WA and NT, and TAS reported ‘syndromic only’ (Figure 1).
‘Syndromic only’ activity is defined as an increase in syndromic surveillance systems with no laboratory confirmed cases. ‘Sporadic’ activity is defined as 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’ activity is defined as outbreaks of influenza or increases in cases in syndromic surveillance systems and recent laboratory-confirmed influenza in a single region of the state.
Figure 1. Map of influenza and ILI activity, by state and territory, during fortnight ending 25 June 2010
Sentinel General Practice SurveillanceIn the week ending 11 July 2010, national ILI consultation rates to sentinel GPs was approximately 8 cases per 1,000 consultations (Figure 2).
Figure 2. Weekly rate of ILI reported from GP ILI surveillance systems from 1 January 2007 to 11 July 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.
WA Emergency DepartmentsRespiratory viral presentations reported in Western Australian EDs continue to show an upward trend (Figure 3). In the week ending 11 July 2010 there were 502 respiratory viral presentations, approximately the same as presentations in the previous reporting week (503).
Figure 3. Number of respiratory viral presentations to Western Australia EDs from 1 January 2007 to 11 July 2010 by week
Source: WA ‘Virus Watch’ Report
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NSW Emergency DepartmentsIn the week ending 9 July 2010, ILI presentations to NSW EDs remained low and similar to levels seen at the same time in 2008 (Figure 4). In June 2010, there were 14 admissions to hospital following presentation to emergency departments with ILI.
Figure 4: ILI presentations to NSW EDs from 2007-2010, by week
Source: NSW Health ‘Influenza Weekly Epidemiology Report
FlutrackingFlutracking, a national online system for collecting data on ILI in the community, reported that ILI levels remained low and stable in the week ending 18 July 2010 (Figure 5).
Figure 5. Rate of ILI symptoms among Flutracking participants by week, from week ending 30 May 2010 to week ending 18 July 2010
Source: Flutracking Interim Weekly Report
National Health Call Centre NetworkThe number of calls to the National Health Call Centre Network (NHCCN) decreased this reporting period (Figure 6), compared to the small spike seen last reporting period.
Although ILI-related calls have been increasing gradually since the start of 2010, the number of ILI calls, and percent of total calls, are at levels similar to late 2009 (Figure 6). Call numbers cannot be compared between early 2009 and early 2010 as not all call centres were online in early 2009. The difference in operating call centre numbers 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 16 July 2010
Note: national data does not include QLD and VIC
Source: NHCCN data
AbsenteeismIn the week ending 7 July 2010, absenteeism remained at levels similar to the previous few weeks. Overall there has been a gradual increasing trend since the beginning of 2010 (Figure 7).
Figure 7. Rates of absenteeism (greater than 3 days absent on sick leave), national employer, from 28 January 2007 to 7 July 2010, by week
SOURCE: Absenteeism data
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Laboratory confirmed influenza
Sentinel Laboratory SurveillanceResults from sentinel laboratory surveillance systems for this reporting period show that 4.9% (22/450) of the respiratory tests conducted over this period were positive for influenza, an increase compared with 3.2% last reporting period (Figure 8).
Figure 8. Total number of specimens tested by sentinel laboratories, and proportion positive, 1 January 2010 to 16 July 2010, by week
SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs
Sentinel laboratories reported 28 specimens positive for influenza during this period, of which 20 were pandemic (H1N1) 2009, 2 were A/H3N2 and 2 were influenza B (Table 1). Sentinel laboratory data are used in addition to NNDSS data to understand the strains circulating in Australia, as approximately 75% of NNDSS notifications are influenza A (untyped).
Table 1. Laboratory respiratory tests that tested positive for influenza
|ASPREN – national||NSW NIC||WA NIC||NT |
(Reported by WA NIC)
|Total specimens tested||14||112||177||N/A||127||20|
|Positive Influenza A||0||1||12||2||7||0|
|Positive Influenza B||0||1||1||0||0||0|
|The most common respiratory virus detected||Rhinovirus||RSV||RSV||N/A||Picornavirus||N/A|
In 2010, a total of 144 specimens have been positive for influenza (of 6445 specimens tested), of which 62% were pandemic (H1N1) 2009 and 28% were A/H3N2 (Figure 9). Sentinel laboratory data are used in addition to NNDSS data to understand the strains circulating in Australia, as approximately 75% of NNDSS notifications are influenza A (untyped).
Figure 9. Percentage of specimens tested by sentinel laboratories influenza positive, 1 January 2010 to 9 July 2010, by subtype
SOURCE: Sentinel laboratory data from ASPREN, NSW NIC, WA NIC, VIC NIC & TAS Labs
Laboratory Confirmed Cases Notified to Health DepartmentsDuring this reporting period, 45 confirmed cases of influenza were notified (2 in NSW, 3 in NT, 24 in QLD, 6 in SA and 10 in WA). They included 17 pandemic (H1N1) 2009, 21 of influenza A (not sub-typed) and 6 of influenza B. Pandemic influenza activity remains low, and sporadic cases of pandemic influenza continue to be reported without evidence of sustained community transmission.
There have been 1,362 confirmed cases of influenza of all types diagnosed during 2010 up to 16 July (Figure 10). Of those, 212 (16%) have been sub-typed as pandemic (H1N1) 2009, 997 (73%) as influenza type A not sub-typed, 9 (1%) as A/H3N2 and 8 (1%) as type A&B. A further 117 (9%) have been characterised as influenza type B and 19 (1%) have been untyped.
Figure 10. Laboratory confirmed cases of influenza in Australia, 1 January 2005 to 16 July 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, the distribution of influenza notifications is consistent across age groups and similar to distributions observed in 2008 (Figure 11). 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.
Figure 11. Laboratory confirmed cases of influenza (pandemic (H1N1) 2009 and seasonal) in Australia, 1 January 2008 to 16 July 2010, by age group
Source: NNDSS and NetEpi (NSW).
2. Influenza severity to 16 July 2010 1
Pandemic (H1N1) 2009
While pandemic (H1N1) 2009 is generally considered a mild disease at the community level, it has had serious consequences for some who experience it. Figures of hospitalisations, ICU admissions and deaths are currently used as indicators of the severity of the disease in Australia (Table 2).
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 37,848 confirmed cases of pandemic (H1N1) 2009 in Australia as at 16 July 2010, including 191 pandemic influenza-associated deaths. Of these, 37,636 cases were reported in 2009 and 212 cases were reported in 2010.
Table 2. Summary of severity indicators of pandemic (H1N1) in Australia, 2009 and 2010 (up to 16 July 2010)
(H1N1) 2009 cases
|Hospitalised cases||ICU cases||Deaths||Confirmed (H1N1) 2009 cases|
|Total number||37,636||13% (4,992/37,636) confirmed cases)||14% |
|Crude rate per 100,000 population||172.1||22.8||3.1||0.9||1.0|
|Median age (years)||21||31||44||53||28|
|Females||51% (19,139/37,636)||51% (2,528/4,992)||53% |
|Vulnerable groups (Indigenous persons, pregnant women & individuals with at least 1 co-morbidity)||n/a||58% (2,892/4,992)||74% |
|Indigenous people~||11% (3,877/34,750)||20% |
(287/1,056 hospitalised females aged
(47/289) hospitalised pregnant women)
|Cases with at least 1 co-morbidity||n/a||46% (2,303/4,992)||67%|
# 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.
~ The denominator for this row is the number of confirmed cases for which Indigenous status is known. In 2010, 59 cases had Indigenous status unknown.
* Includes women in the post-partum period.
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1Note 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.
Influenza HospitalisationsThe Influenza Complications Alert Network (FluCAN) reported one influenza A (not subtyped) and three pandemic (H1N1) 2009 hospitalisations from selected hospitals for the week ending 16 July 2010. For the period of 1 March to 16 July 2010, FluCAN has reported a total of 24 influenza hospitalisations (Figure 12). Of those, 14 have been associated with pandemic (H1N1) 2009, including 3 with ICU admission.
Figure 12. Number of influenza hospitalisations, sentinel hospitals, Australia, 1 March to 16 July 2010
Source: Influenza Complications Alert Network (FluCAN). Data from 14 sentinel hospitals from all jurisdictions.
Note: two cases have been retrospectively added for the first week of March.
Intensive care admissionsThe Australian and New Zealand Intensive Care Society (ANZICS) has reported a total of ten ICU admissions for influenza in 2010, of which none occurred during this reporting period. In total, five ICU admissions have been associated with pandemic (H1N1) 2009 and five with influenza A (not subtyped) (Figure 13).
Of the 5 pandemic (H1N1) 2009 ICU admissions in 2010, 3 had known co-morbidities and the median age at admission was 29 years (range 10-59).
Figure 13. Number of ICU admissions for influenza, ANZICS, Australia, 1 January to 17 July 2010
Source: Australian and New Zealand Intensive Care Society (ANZICS) data base
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Deaths associated with influenza and pneumoniaDeath registration data show that for the week ending 25 June 2010, there were 104 pneumonia or influenza associated deaths per 1,000 deaths in NSW, which is below the seasonal threshold of 123 per 1,000 (Figure 14).
Figure 14. Rate of deaths classified as influenza and pneumonia from the NSW Registered Death Certificates, 2005 to 25 June 2010
Source: NSW ‘Influenza Monthly Epidemiology Report’
Typing and antigenic characterisation - WHO Collaborating Centre for Reference & Research on Influenza (WHO CC) in MelbourneFrom 1 January to 18 July 2010, there were 97 Australian influenza isolates subtyped by the WHO CC (Table 3).
Table 3. Typing of influenza isolates from the WHO Collaborating Centre, from 1 January 2010 to 18 July 2010
|Pandemic (H1N1) 2009||1||1||39||11||0||1||10||11||74|
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 20 pandemic (H1N1) 2009 isolates has shown 19 to be the A/California/7/2009-like strain and one a low reactor version of this strain. Antigenic characterisation of 8 type A/H3N2 isolates has shown one to be the A/Perth/16/2009-like and 7 to be the A/Perth/16/2009-like low reactor version of the strain.
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International VirologyIn the week ending 26 June 2010, based on FluNet reporting by National Influenza Centres from 24 countries, 41.2% of positive specimens were typed as influenza B and 58.8% were typed as influenza A. Influenza B detections have decreased in the past week (56.9% of all detections in China). In the Southern Hemisphere, there is an increasing number of influenza A virus detections with co-circulation of pandemic A(H1N1) and seasonal A(H3N2) viruses.
In China, influenza B accounted for 56.5% of all influenza viruses detected in the week to 4 July 2010. From 1 January 2010 to 4 July 2010, 3070 influenza B viruses have been antigenically characterised. Of those, 2,655 (86.5%) were B/Victoria viruses, including 49.2% (1307) related to B/Malaysia/2506/2004-like and 50.8% (1348) related to B/Brisbane/60/2008 (included in 2010 Southern Hemisphere seasonal influenza vaccine). The remaining 415 (13.5%) were B/Yamagata viruses related to B/Florida/4/2006-like.1.
Antiviral Resistance – Pandemic (H1N1) 2009
The WHO has reported that 298 oseltamivir resistant pandemic (H1N1) 2009 viruses have been detected and characterised worldwide since May 2009. All of these isolates showed the same H275Y mutation and all remain sensitive to zanamivir.2
The WHO Collaborating Centre in Melbourne has reported that from 1 January 2010 to 18 July 2010, no isolates (out of 40 tested) have shown resistance to oseltamivir or zanamivir by enzyme inhibition assay (EIA) and two isolates (out of 35 tested) have shown the H275Y mutation known to confer resistance to oseltamivir.
4. International Influenza Surveillance
The WHO has reported that have been over 18,337 deaths associated with pandemic (H1N1) 2009 influenza worldwide. Overall pandemic activity worldwide remains low.2.
- Pandemic and seasonal influenza viruses have been detected sporadically or at very low levels during the past month.2.
- Active circulation of pandemic influenza virus persists in South Asia, Central America and West Africa. 2.
- In China, Hong Kong, Taiwan and the Republic of Korea, seasonal influenza B continued to circulate at low levels.
- In India, transmission of pandemic influenza virus remains active but stable in the southern state of Kerala.
- In Singapore, substantial co-circulation of pandemic and seasonal influenza H3N2 viruses was detected in May and June 2010.
- In South Africa, a sharp increase in the levels of seasonal influenza (H3N2 and type B) viruses occurred during late June, reaching a peak detection rate of approximately 50%. By the second week of July the rate had dropped to approximately 40%.2.
- In New Zealand, influenza activity is continuing to increase, with rates of ILI presentations to GPs and hospitals gradually increasing. Two pandemic (H1N1) 2009 related deaths have been reported so far in 20103.
- In Chile and Argentina, ILI rates remained low, with reports of RSV as the predominantly circulating respiratory virus.
5. Data considerationsThe 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 firstname.lastname@example.org.
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.
NetEpiIn 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.
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.
Data AnalysisAnalysis 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.
Sentinel Laboratory Surveillance dataLaboratory testing data are provided weekly directly from PathWest (WA & NT), VIDRL (VIC), ICPMR (NSW), sentinel Tasmanian laboratories, and ASPREN (national).
WHO Collaborating Centre for Reference & Research on Influenza (WHO CC)Data are provided weekly to the Surveillance Branch from the WHO CC.
Sentinel General Practice SurveillanceThe Australian Sentinel Practices Research Network (ASPREN) has Sentinel GPs who report ILI presentation rates in NSW, 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 dataWA - 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.
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AbsenteeismA 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.
National Health Call Centre NetworkA 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.
FluTrackingFluTracking 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.
FluCANThe 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.
Australian and New Zealand Intensive Care Society data (ANZICS data)The Australian and New Zealand Intensive Care Society provides 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.
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6. References1 Chinese National Influenza Centre Influenza Weekly Report 20 June 2010. Available from: http://www.cnic.org.cn/eng/ Accessed 21 June 2010.
2 WHO Pandemic (H1N1) 2009 - Update 109 & Virological Surveillance Weekly Update. Available from http://www.who.int/csr/don/en/ Accessed 20 July 2010.
3Pandemic Influenza H1N1 2009 (swine flu) - Update 195. Available from http://www.moh.govt.nz/moh.nsf/indexmh/influenza-a-h1n1-update-195-160710
Accessed 20 July 2010.