Report No. 13
Week ending 7 August 2009
A print friendly version of this report is available as a PDF (205 KB)Key Indicators
The counting of every case of pandemic influenza is no longer feasible in the PROTECT phase. Influenza activity and severity in community is instead monitored by the surveillance systems listed below.Is the situation changing? |
Indicated by: laboratory confirmed cases reported to NetEpi/NNDSS; GP Sentinel ILI Surveillance; and ED presentations of ILI at sentinel hospitals (NSW and WA). Laboratory data are used to determine the proportion of pandemic (H1N1) 2009 circulating in the community. |
|---|---|
How severe is the disease, and is severity changing? |
Indicated by: number of hospitalisations, ICU admissions and deaths from sentinel hospital surveillance; emergence of more severe clinical picture in hospitalised cases and ICU admissions. |
Is the virus changing? |
Indicated by: emergence of drug resistance or gene drift/shift from laboratory surveillance. |
What is ahead? |
Forward projections of cases, morbidity and mortality. |
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Key Points
Is the situation changing?
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How severe is the disease?
* Most cases admitted to an ICU would be ventilated.
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Is the virus changing?
To date in Australia, all of the 111 pandemic influenza isolates tested are sensitive to the neuraminidase inhibitors oseltamivir and zanamivir.WHO has received formal notification of 7 cases of oseltamivir resistance pandemic (H1N1) 2009 viruses to date (1 in Singapore, 1 in Denmark, 1 in Hong Kong, 1 in Canada and 3 in Japan). Media sources have reported that China has informally alerted WHO of the discovery of a small number of additional oseltamivir resistance pandemic (H1N1) 2009 viruses.
What is ahead?
With a 20% clinical attack rate and no intervention; it has been estimated that by the end of winter 1 in 5 Australian (4.3 million) could become infected with the pandemic virus, leading to 40 to 80,000 hospitalisations, and 6,000 deaths. Currently the number of hospitalisations and deaths are tracking below these estimations, suggesting that efforts to protect the vulnerable are effective.Top of page
Current influenza activity in Australia – Is the situation changing?
Notifications of confirmed pandemic (H1N1) 2009 and seasonal influenza
As of 7 August 2009 there were 25,055 confirmed cases of pandemic (H1N1) 2009 in Australia, including 85 deaths. Notifications of laboratory confirmed pandemic (H1N1) 2009 have decreased nationally over the last week. The number of cases reported represents only a small proportion of pandemic (H1N1) 2009 circulating in the community.The national epidemic curve shows the jurisdictional distribution of confirmed cases of pandemic (H1N1) 2009 over time in Australia (Figure 1). The epidemic curve shows several peaks, however the pattern is a surveillance artefact due to a change in testing policy. The majority of earlier confirmed cases occurred in Victoria, where case reporting peaked in late May before declining rapidly in early June. This change was due to targeted laboratory testing implemented on 3 June 2009 as part of the modified SUSTAIN phase.
Figure 1. Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 7 August 2009 by jurisdiction
Source: NetEPI database
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As Figure 2 shows, influenza activity in 2009 started earlier than in 2008 and there was a rapid increase in the number of confirmed influenza cases (both seasonal and pandemic (H1N1) 2009) from week 21 (starting 16 May 2009). The high number of seasonal influenza seen during May and June are most likely due to the increase in testing for pandemic (H1N1) 2009.
Laboratory confirmed notifications of influenza are currently at 1.6 times the 5 year rolling mean.
Figure 2: Influenza activity in Australia, by reporting week, years 2007, 2008 and 2009*
* Data on pandemic (H1N1) 2001 cases is extracted from NetEPI; data on seasonal influenza is extracted from the NNDSS.
Source: NNDSS and NetEPI databases
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 will not reflect how many people in the community have acquired pandemic (H1N1) 2009 infection, but reflects the number of confirmed cases among those most at risk.
As the counting of every case is no longer feasible in the PROTECT phase. Influenza activity, including Influenza Like Illness (ILI) activity in the community is instead monitored by surveillance systems including:
- GP Sentinel ILI surveillance;
- Emergency Department presentations of ILI at sentinel hospitals (NSW and WA); and
- Absenteeism rates.
- Laboratory data are used to determine the proportion of pandemic (H1N1) 2009 circulating in the community.
Influenza Like Illness activity in Australia
Sentinel General Practice
ILI presentations to General Practitioners remain high but lower than 2007 rates nationally. Decreases have been seen in Tasmania, the Northern Territory and VIDRL GPs this reporting period.Combined data available from the Australian Sentinel Practices Research Network (ASPREN), the Northern Territory GP surveillance system and VIDRL, up until 2 August 2009, show that nationally, influenza like Illness (ILI) consultation rates have increased this reporting period and are below levels seen in 2007 (Figure 3). In the last week, the presentation rate to sentinel GPs in Australia was approximately 33 cases per 1,000 patients seen.
Figure 3. Rate of ILI reported from GP ILI surveillance systems from 2007 to 2 August 2009 by week*
* Delays in the reporting of data may cause data to change retrospectively. As data from the NT and the VIDRL surveillance systems are combined with ASPREN data, rates may not be directly comparable across 2007, 2008 and 2009.
SOURCE: ASPREN, NT, VIDRL
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Figure 4 does not include GPs from Victoria reporting to ASPREN or VIDRL. Consultation rates of ILI (excluding Victoria) have increased sharply and are higher than in 2007 and 2008. Further analysis of the ILI data showed levels in Tasmania and the Northern Territory dropped in this period (Figure 5). In Victoria, the rate of ILI from Victorian ASPREN GPs have increased while rates reported by VIDRL GPs have dropped.
Care should be taken when interpreting Figure 5 graphs as analysing ASPREN data by States and Territories results in small amounts of data for some jurisdictions. The last data point can also change retrospectively due to data lag.
Figure 4. Rate of ILI reported from ASPREN and NT (excluding VIC) from 2007 to 2 August 2009 by week
SOURCE: ASPREN, NT
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Figure 5. Rate of ILI reported from ASPREN by State from 2007 to 2 August 2009 by week
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SOURCE: ASPREN (VIC) & VIDRL
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Emergency departments
Trends in ILI presentations to EDs varied this reporting period, with WA (Figure 5) reporting an increase, SA remaining relatively stable and NSW (Figure 6) reporting a decrease.The number of ILI presentations reported in Western Australian EDs has increased in the week ending 2 August 2009 to its highest point this year and is higher than at the same time in 2007 and 2008 (Figure 6). The proportion of ILI presentations admitted to hospital decreased from 5.7% to 4.9%.
Figure 6. Number of Emergency Department presentations due to ILI in Western Australia from 1 January 2007 to 2 August 2009 by week
In early July 2007 (week 26), several deaths associated with influenza infection were reported in children from Western Australia. The public response to these deaths could account for the sudden increase in ILI presentations to Perth EDs in 2007.
SOURCE: WA ‘Virus Watch’ Report
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In the week ending 24 July 2009, ILI presentations to New South Wales EDs decreased (rate 38 per 1,000 presentations) (Figure 7). Presentations were mainly for mild illnesses and 8% of presentations with ILI were admitted.
Figure 7. Rate of ILI diagnosed in people presenting to selected Emergency Departments, NSW 1 January 2005 to 24 July 2009 by month*
* Emergency department data are preliminary and may be updated in later weeks.
SOURCE: NSW HEALTH ‘NSW Influenza Surveillance Report’
ILI presentations to South Australian EDs remained relatively stable this reporting period with 217 presentations compared to 214 presentations in the previous week. The number of admissions increased from 13 to 19.1
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Absenteeism
Absenteeism rates have increased in the last week, but at a slower rate than previous weeks. Rates are much higher than at the same time in 2008 but at around the same level as in 2007 (Figure 8).Figure 8. Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 22 July 2009, by week
SOURCE: Absenteeism data
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Laboratory surveillance
How much ILI and influenza is due to pandemic (H1N1) 2009?
As shown in Table 1, the proportion of respiratory tests positive for influenza varied between jurisdictional reporting laboratories and ranged from 21% to 42% for this reporting period.Of those tests that were positive for Influenza A, the proportion of tests that were pandemic (H1N1) 2009 continues to increase in most jurisdictions, and varied between jurisdictions from 70% (NT) to 97% (WA).
The proportion of pandemic (H1N1) 2009 to seasonal influenza varies across jurisdictions and continues to increase in all States and Territories with the exception of Victoria. This proportion is used as an indicator to help determine if a person has influenza, how likely it is to be pandemic (H1N1) 2009. The proportion of pandemic (H1N1) 2009 to seasonal influenza as reported by the jurisdictions is shown in Table 1. The average proportion of confirmed influenza in Australia which was pandemic (H1N1) 2009 increased slightly to 83% (Table 1).
Over the last two weeks, for the days on which surveillance testing was conducted, ASPREN GPs reported 174 people presenting with ILI. Of these, 53% (92/174) were tested for influenza. Twenty-seven per cent (25/92) of these cases were influenza positive; 92% (23/25) were pandemic (H1N1) 2009 and 8% (2/25) were influenza A unspecified.
Table 1. Laboratory tests that tested positive for influenza A and pandemic (H1N1) 2009
| ASPREN – national | NSW report^ | VIDRL Sentinel GP # | WA NIC | NT NIC | |
|---|---|---|---|---|---|
Latest report |
|||||
| Number of specimens tested | 92 |
2637 |
45 |
n/a |
n/a |
(at 31/7) |
(at 9/8) |
||||
| % tested which were Influenza A | 27% |
21% |
42% |
558 |
37 |
(at 7/8) |
(at 7/8) |
||||
| % tested which were pandemic (H1N1) 2009 | 92% |
79% |
89% |
97% |
70% |
Previous report |
|||||
| Number of specimens tested | 80 |
3755 |
59 |
n/a |
n/a |
(at 24/7) |
(at 26/7) |
||||
| % tested which were Influenza A | 41% |
24% |
41% |
519 |
74 |
(at 31/7) |
(at 31/7) |
||||
| % tested which were pandemic (H1N1) 2009 | 88% |
70% |
100% |
96% |
69% |
* ASPREN tests are collected every Tuesday. Results are reported for a rolling fortnight as data changes retrospectively.
^ NSW Influenza Report available from: http://www.emergency.health.nsw.gov.au/swineflu/index.asp
# VIDRL Influenza Report available from: http://www.vidrl.org.au/surveillance/flu%20reports/flurpt09/flu09.html
^^ 8 Influenza A specimens were untyped.
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The proportion of pandemic (H1N1) 2009 compared with seasonal influenza in Australia is very similar to that reported by a number of other countries in both the Northern and Southern Hemispheres. Canada is reporting that pandemic (H1N1) 2009 represents 98.7% of all influenzas,2 while Chile is reporting that 93% of the total circulating influenza viruses in people aged over 5 years are pandemic (H1N1) 2009.3 In New Zealand, pandemic (H1N1) 2009 represents 68% of influenza viruses reported from sentinel surveillance and 61% of influenza viruses reported in non-sentinel surveillance.4
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How severe is the disease, and is severity changing?
Pandemic morbidity (hospitalisations)
Hospitalisations of Pandemic (H1N1) 2009 confirmed cases
As of 7 August 2009, the jurisdictions have reported that 3,009 confirmed cases of pandemic (H1N1) 2009 have been hospitalised (this figure includes people who are hospitalised for associated conditions). The number of cases per day requiring hospitalisation has been increasing since mid June. Four hundred and eighty four additional new cases have been hospitalised over the last week (Figure 9* ). This is a decrease from the previous week when an additional 649 cases were hospitalised.* The numbers hospitalised should be treated with caution as there may be case ascertainment bias in the reporting of confirmed cases being hospitalised. All paediatric cases admitted to hospital are being tested for pandemic (H1N1) 2009 while not all hospitalised adults might be tested. There may be a significant underestimation of the numbers of adults hospitalised from pandemic (H1N1) 2009 due to limited testing.
Indigenous Australians are approximately 5 times more likely than non-Indigenous Australians to be hospitalised for pandemic (H1N1) 2009. The states and territories have reported that 346 (11.5%) of all 3,009 cases hospitalised since the beginning of the outbreak were Aboriginal and/or Torres Strait Islander.
For comparative purposes, for the period 2000-01 to 2006-07, an average of 1,925 people with influenza were admitted to hospital each year. For all influenzas* and pneumonias,** for the same period, an average of 73,271 people were admitted to hospital.5
* ICD10-AM codes J10, J11
** ICD10-AM codes J12-J18
Figure 9. Hospitalisations of pandemic (H1N1) 2009, 15 June 2009 to 7 August 2009, Australia
* The jurisdictions report directly to the National Incident Room, Commonwealth Department of Health and Ageing, on hospitalisations and numbers admitted to ICUs.
Source: Jurisdictions
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Age and sex distribution of hospitalised confirmed cases
Limited further information is available for 2,052 (68%) of the 3,009 confirmed cases hospitalised since the beginning of the outbreak. Of these cases, the overall hospitalisation rate is 9.6 per 100,000 population with the highest rates in males aged less than 5 years of age (31.5 per 100,000 population). The median age of hospitalised cases is 31 years (range 0-98). Figure 10 illustrates that the age distribution of hospitalised cases of pandemic (H1N1) 2009 is different to previous influenza seasons. In comparison with the 2004-2007 influenza season, young children aged less than 5 years of age continue to be hospitalised at a higher rate than other age groups but for pandemic (H1N1) 2009 there is a peak in the 50 to 60 years age group and a marked decrease in those aged more than 75 years.The United Kingdom has also reported that the highest hospitalisation rates are in those aged less than 5 years of age (10.6 per 100,000 population for the seven days to 03 August 2009). They continue to have a higher proportion of hospitalised cases in the 65+ year age group when compared with Australia (16% compared with 8%). Chile has reported hospitalisation rates of 6.7 per 100,000 population with a median age of 31 years for hospitalised cases.
Figure 10. Age specific rates of hospitalised confirmed cases of pandemic (H1N1) 2009 to 7 August 2009, compared with average annual age specific rates of hospitalisations from seasonal influenza 2004-05 to 2006-07*, Australia
* The rates for pandemic (H1N1) 2009 are for a six week period 15 June to 7 August 2009 whereas the rates for seasonal influenza are averaged annual rates (i.e. for a full influenza season).
Source: NETEPI database
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Information on length of stay is available for 51% of hospitalised cases (n=1,048). The median length of stay in hospital is 3 days (range 1-47 days). Forty seven per cent (n=116) of children aged less than 5 years of age have been hospitalised for less than 3 days and 9% (n=21) have been hospitalised for more than 7 days. Twenty three per cent (114/497) of hospitalisations in those aged 30 years and over have resulted in stays of more than 7 days (Figure 11).
Figure 11. Hospitalised confirmed cases of pandemic (H1N1) 2009, by length of hospital stay and age group, to 7 August 2009, Australia
Source: NETEPI database
Pregnancy as a risk factor for pandemic (H1N1) 2009
Seventy four (4%) of the 2,052 hospitalised confirmed cases for whom further information was known were pregnant women. For the month of July, pregnant women accounted for 35% of hospitalised confirmed cases for all women aged between 25 to 35 years. Information on gestation is available for 50 of the 74 cases. Twelve per cent (n=6) were in their first trimester (weeks 1-12); 28% (n=14) were in their second trimester (weeks 13-26); and 60% (n=30) were in their third trimester (weeks 27-40) (Figure 12). Nine pregnant women were admitted to ICU. Eight were in their second or third trimester and information on gestation was not available for one woman. Pregnant women stayed an average of 12.5 days in ICU (range 3-24 days). One pregnant woman is known to have died.Figure 12. Hospitalised confirmed cases of pandemic (H1N1) 2009 in pregnant women by weeks of gestation, to 7 August 2009, Australia
Source: NETEPI database
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Paediatric hospital admissions
Since reporting began in 2009, 85 children have been reported as hospitalised with complications from influenza by the Australian Paediatric Surveillance Unit (APSU). A total of 56 cases for which admission data is provided is shown in Figure 13.Of the 62 cases for which data is available, the average age of children admitted to hospital was four years, with an age range from one month to 16 years. Complications were mostly pneumonia and encephalitis. Twenty-two of the 55 (40%) cases for which data is available had underlying conditions.
Figure 13. Number of paediatric hospital admissions APSU, 11 March 2009 to 6 August 2009, by week
SOURCE: APSU
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Confirmed cases requiring intensive care
In Week 32 (week ending 7 August 2009), an average of 112 hospitalised cases required intensive care on any given day This does not represent the number of new cases requiring admittance to an Intensive Care Unit (ICU) but is a repeated measure of the prevalence of confirmed cases in an ICU on a particular day. The length of stay in an ICU will differ depending on the severity of a particular case. Over the last week, the average proportion of hospitalised cases in an ICU Most cases admitted to an ICU would be ventilated on any day was 27%, which was the same as the previous week (Figure 11). Information on the percentage of hospitalised cases admitted to an ICU since the beginning of the pandemic is available for two States. In New South Wales the percentage of hospitalised cases admitted to an ICU is 14.2% and for Queensland the percentage is 13.3%. (Figure 14)Figure 14. Proportion of hospitalised pandemic (H1N1) 2009 confirmed cases who are in ICU, by day, 15 June 2009 to 7 August 2009, Australia
* The jurisdictions report directly to the National Incident Room, Commonwealth Department of Health and Ageing, on hospitalisations and numbers admitted to ICUs.
Source: Jurisdictions
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Snapshot on Queensland hospitalised confirmed cases*
Eight hundred and three people have been hospitalised in Queensland for pandemic (H1N1) 2009 between 25 May 2009 and 7 August 2009, an age standardised rate of 18.6 per 100,000 population. Fifty five per cent (n=441) of hospitalisations were in females, an age standardised rate of 20.6 per 100,000 population. Forty five per cent (n=362) of hospitalisations were in males, an age standardised rate of 16.9 per 100,000 population.Of these 803 hospitalised cases, co-morbidities were reported in 61% (n=491) of cases. Co-morbidities included chronic respiratory 49% (n=239); diabetes 14% (n=70); pregnancy 11% (n=54); chronic cardiac 11% (n=52); immunocompromised 10% (n=50); morbid obesity 8% (n=38); and renal 5% (n=25). Information on the length of time between onset of symptoms and admittance to hospital were available for 531 confirmed cases. Fifty three per cent (280/531) of these cases were admitted within 48 hours of onset of symptoms.
Figure 15 illustrates that the 0-4 years age group is more likely to be hospitalised but that the length of stay for this age group is usually of less than 3 days duration. Twenty three per cent (n=185) of cases were hospitalised for less than 3 days; 40% (n=322) for 3-7 days; 10% (n=78) for 8-13 days; and 8% (n=62) for 14 or more days. These figures include cases that are still hospitalised.
Of these hospitalised cases, 107 were admitted to an ICU or special care with twice as many male being admitted than females. The median length of stay in ICU or special care was 7 days (range 1-34 days). The age of cases admitted to ICU ranged from 0-84 years with the highest proportion of cases in the 50-54 year age group (14%, n=15), followed by the 25-29 year age group and the 45-49 year age group, which each accounted for 13% (n=14) of the cases. Forty two per cent (n=45) of cases in ICU had no reported co-morbidities.
* Queensland has been able to provide greater detail on hospitalised cases than other States and Territories, enabling more in-depth analysis of hospitalised cases.
Figure 15. Hospitalised confirmed cases of pandemic (H1N1) 2009, by length of hospital stay and age group, to 7 August 2009, Queensland
Source: Qld Health
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Pandemic Mortality
Deaths associated with pandemic (H1N1) 2009
Eighty five people in Australia.* with confirmed pandemic (H1N1) 2009 infection died between 19 June 2009 and 7 August 2009, with 30 reported in New South Wales, 18 in Victoria, 15 in Queensland, 8 in South Australia, 5 in Western Australia, 4 each in the Northern Territory and Tasmania, and 1 in the Australian Capital Territory.** Reports from the jurisdictions in Australia indicate that most of the cases had underlying medical conditions; including cancer, diabetes mellitus and morbid obesity. Of the 85 deaths, 10 (11.8%) were Indigenous.**** For the most recent figures on hospitalisations and deaths please access the latest Situation Report at http://www.healthemergency.gov.au/internet/healthemergency/publishing.nsf/Content/updates
** This death has yet to be confirmed by the Coroner.
*** It is estimated that 2.4% of the total Australian population are Aboriginal and/or Torres Strait Islander.
Further information was available on 60 of the 85 deaths in Australia. Sixty three per cent (n=38) of deaths were in males. The median age of confirmed cases that died was 56 years (range 3-86 years). This compares with deaths from seasonal influenza where the median age, for the period 2001-2006, was 83 years. As illustrated in Figure 16, the highest proportion of deaths (18%) have occurred in the 55-59 year age group (n=11). Most deaths have occurred in those aged between 35 to 79 years. The pattern of deaths in the different age groups is very different to the age distribution of hospitalisations and confirmed cases.
Figure 16. Number of deaths among confirmed cases of pandemic (H1N1) 2009, by age group and sex, compared with total pandemic (H1N1) 2009 notifications by age group, to 7 August 2009, Australia
Source: NETEPI database
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Deaths associated with influenza and pneumonia
There are difficulties estimating the number of deaths due to influenza in Australia. Deaths coded as being due to laboratory confirmed influenza are known to underestimate the true number. Influenza may not be listed on the death certificate if it wasn’t recognised as the underlying cause. Coding of pneumonia and influenza provides an additional measure, although this will overestimate the number of deaths as it will include other causes of pneumonia.The median number of annual deaths in Australia for the years 2001 to 2006 from influenza and pneumonia is 3,089 and for laboratory diagnosed influenza is 40. In 2007 (the latest year for which data has been released) there were 2,623 deaths with influenza and pneumonia as the underlying cause of death. In 2007, influenza and pneumonia was the 13th leading cause of death in Australia (Source: ABS, Causes of Death 2007). Mortality figures are likely to be an underestimate due to inherent difficulties in assigning causes of death and therefore appropriate ICD codes. ABS mortality data are released two years in arrears.
In Western Australia, in the third week of July, pneumonia and influenza deaths accounted for 16.9% of all deaths compared to 19.9% for the same time in 2008 (Figure 17).
Figure 17: Total number of deaths classified as influenza and pneumonia, WA Registry of Births, Deaths and Marriages, 1 January 2008 to July 2009
SOURCE: WA ‘Virus Watch’ Report
Figure 18: Rates of deaths classified as influenza and pneumonia, NSW Registry of Births, Deaths and Marriages, 1 January 2004 to 17 July 2009
SOURCE: NSW Health ‘Weekly Influenza Epidemiology Report’
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Is the virus changing?
Laboratory Confirmed Influenza
It is not possible to determine accurately the number of notifications due to seasonal influenza. Increasingly, not all influenza viruses are subtyped and the large proportion of influenza A (12,599 notifications) reported to NNDSS could be either pandemic (H1N1) 2009 or seasonal influenza. Laboratory reports in recent weeks estimate that 83% of all influenza positive tests are due to pandemic (H1N1) 2009.From 1 January to 7 August 2009, type A is the predominant seasonal influenza type reported by all jurisdictions. Of type A notifications for which there is subtyping information in NNDSS, 2.0% (257) are seasonal H1N1 and 3.6% (454) are H3N2.
Antiviral Resistance
Pandemic (H1N1) 2009
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Seasonal Influenza
The last WHO report on oseltamivir resistance to seasonal strains was released on 4 June 2009, during the Northern Hemisphere influenza season 2008-2009. This report stated that 96% of seasonal influenza A (H1N1) isolates tested from 36 countries worldwide were resistant to oseltamivir.9In New Zealand, all of the 53 seasonal influenza A (H1N1) isolates tested up to 2 August 2009 were resistant to oseltamivir.10
The US CDC reported in the week ending 1 August that 99.6% of the seasonal A(H1N1) tested was resistant to oseltamivir and 100% of the Influenza A(H3N2) tested was resistant to adamantanes.11
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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. Please note, the pandemic (H1N1) 2009 and seasonal influenza elements of this report are based on data available as at 27 July 2009. 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.auNetEpi
All jurisdictions except QLD are reporting pandemic (H1N1) 2009 cases using NetEpi, a web-based outbreak case reporting system. Data from jurisdictional systems are being imported into NetEpi by VIC, NSW and WA, the remainder are entering directly into NetEpi. Qld ceased reporting into NetEpi on 6 July 2009.Analyses of Australian cases are based on clinical onset date, if this information is available. Where an onset date is not available, notification date has been used. Victorian cases use a calculated onset date which is the earliest available date calculated from specimen date, onset date, notification date or detection date. This assumption was made for all calculations and data on which the figures are based.
State and Territory reporting
The jurisdictions report directly to the National Incident Room, Commonwealth Department of Health and Ageing, on hospitalisations, numbers admitted to ICUs and deaths.National Notifiable Diseases Surveillance System (NNDSS)
NNDSS comprises of notifications from jurisdictions of laboratory-confirmed influenza cases. Laboratory confirmed influenza is notifiable in all jurisdictions in Australia. Confirmed pandemic (H1N1) 2009 cases are being received from all jurisdictions through NNDSS except for Victoria and New South Wales.Laboratory Surveillance data
Laboratory testing data are extracted from the ‘NSW Influenza Report’ and ‘The 2009 Victorian Influenza Vaccine Effectiveness Audit Report’ (VIDRL).Sentinel General Practice Surveillance
The Australian Sentinel Practices Research Network (ASPREN) has Sentinel GPs who report influenza-like-illness (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 2009 may be different from that of previous years. ASPREN data are sent to the Surveillance Branch on a weekly basis. Northern Territory GP surveillance data are sent to the Surveillance Branch on a weekly basis. VIDRL influenza surveillance data are sent to the Surveillance Branch on a weekly basis.A new testing protocol introduced through ASPREN requires GPs to test all patients presenting with an ILI on one day of the week. These data should provide a cross section of age, sex and severity of patients who seek GP assistance for ILI. This system is in the early stages of implementation and will be further developed over coming weeks.
Sentinel Emergency Department (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 8 Perth Emergency Departments (EDs).
- NSW - ED surveillance data are extracted from the ‘NSW Influenza Surveillance Report’. This report is provided weekly. The New South Wales Influenza Surveillance Program collects data from 49 EDs across New South Wales.
- SA – ED surveillance data are extracted from the ‘South Australian Seasonal Influenza Report’. This report is provided weekly. The South Australian Influenza Surveillance Program collects data from 4 EDs in South Australia.
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.Mortality data
Mortality data are extracted from the NSW Health ‘Weekly Influenza Epidemiology Report’ and the WA ‘Virus Watch’ Report.Paediatric hospital admissions data
Reports of ICU admissions are provided to the Surveillance Branch on a weekly basis by the Australian Paediatric Surveillance Unit. APSU conducts surveillance of severe complications of influenza in children aged 15 years and under. Surveillance began on 1 June 2009.Top of page
References
1. South Australian Seasonal Influenza Report No.11. Available from: http://www.dh.sa.gov.au/pehs/notifiable-diseases-summary/flu-resp-intro.htm Accessed 12 August 2009.2. Canada Public Health Agency, Flu Watch: http://www.phac-aspc.gc.ca/fluwatch/08-09/. Accessed 17 July 2009.
3. Sociedad Chilena de Infectologia. Available at http://www.sochinf.cl/sitio/. Accessed 30 July 2009.
4. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php. Accessed 30 July 2009.
5. Australian Institute of Health and Welfare (AIHW) National Hospital Morbidity Database. Available at: http://www.aihw.gov.au/hospitals/datacubes/index.cfm
6. The Canadian Press. Singapore, China find t H1N1 viruses: WHO. Available from http://www.google.com/hostednews/canadianpress/article/ALeqM5ga4fc-CuD_2uVK_dOPlbPaGheujw. Accessed 13 August 2009.
7. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php. Accessed 12 August 2009.
8. CDC Influenza reports http://www.cdc.gov/h1n1flu/pubs/. Accessed 12 August 2009.
9. WHO Influenza A virus resistance to oseltamivir and other antiviral medicines, 4 June 2009. Available from:
http://www.who.int/csr/disease/influenza/en/. Accessed 12 August 2009.
10. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: http://www.surv.esr.cri.nz/virology/influenza_weekly_update.php. Accessed 12 August 2009.
11. CDC Influenza reports http://www.cdc.gov/h1n1flu/pubs/. Accessed 12 August 2009.
12. PAHO Regional Update. Pandemic (H1N1) 2009. Epidemiological Week 29 (July 31 2009). Available from: http://new.paho.org/hq/index.php?option=com_content&task=view&id=1684&Itemid=1167. Accessed 12 August 2009.
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