Australian influenza report 2009 - 24 to 30 October 2009 (#25/09)

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. It is produced weekly from May to October. A more in-depth end of season report is also published in Communicable Diseases Intelligence.

Page last updated: 10 November 2009

Report No. 25
Week ending 30 October 2009

A print friendly version of this report is available as a PDF (243 KB)

Is the situation changing?
Indicated by: laboratory confirmed cases reported to NetEpi/NNDSS; Sentinel syndromic surveillance systems GP Sentinel ILI Surveillance; and ED presentations of ILI at sentinel hospitals (NSW and WA). Laboratory data are used to determine the proportion of influenza and 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
Is the virus changing?
Indicated by: emergence of drug resistance or gene drift/shift from laboratory surveillance.

Top of page

Latest data


  • As of 30 October 2009 there were 37,141 confirmed cases of pandemic (H1N1) 2009 and 187 deaths reported in Australia.

      New Hosp
    (indigenous)
    New ICU
    (indigenous)
    New Deaths
    (indigenous)
    Cum Hosp
    (indigenous)
    Cum ICU
    (indigenous)
    Cum Deaths
    (indigenous)
    ACT
    0
    (0)
    0
    (0)
    0
    (0)
    61  
    (0)
    1
    (0)
    2
    (0)
    NSW
    11
    (0)
    0
    (0)
    0
    (0)
    1288 
    (101)
    245
    (-)
    51
    (5)
    NT
    3
    (3)
    0
    (0)
    0
    (0)
    309   
    (319)
    47
    (36)
    6
    (4)
    Qld
    0
    (0)
    0
    (0)
    0
    (0)
    1243 
    (158)
    162
    (-)
    41
    (7)
    SA
    0
    (0)
    0
    (0)
    0
    (0)
    547 
    (44)
    77
    (9)
    29
    (5)
    Tas
    0
    (0)
    0
    (0)
    0
    (0)
    108
    (2)
    9
    (0)
    7
    (0)
    Vic
    -
    (-)
    -
    (-)
    -
    (-)
    514
    (4)
    118
    (-)
    24
    (0)
    WA
    0
    (0)
    0
    (0)
    0
    (0)
    862
    (165)
    79
    (7)
    27
    (3)
    Aus
    14
    (3)
    0
    (0)
    0
    (0)
    4932
    (793)
    738
    (52)
    187
    (24)

    NOTE: Numbers in brackets, eg (0), indicate Indigenous figures.
    Victoria are no longer reporting current hospitalisations.



    Top of page

    Key Issues

  • Increasing influenza activity levels are being experienced in many countries in the Northern Hemisphere, while activity in the Southern Hemisphere is low. Vaccine programs have commenced or are commencing in many countries around the world. (see International Section)
  • Researchers in the USA have reported that an oseltamivir-resistant pandemic (H1N1) 2009 virus infection passed from person-to-person was identified from the US summer wave. The researchers have stated that this is the first of such cases and raises the possibility that widespread resistance will render the anti-viral drug, oseltamivir, less useful in combating the pandemic (H1N1) 2009 virus.1 This also strengthens the case for vaccination for the prevention of pandemic (H1N1) 2009.


    Top of page

    Summary

    Is the situation changing?

    As of 30 October 2009:
  • There were 37,141 confirmed cases of pandemic (H1N1) 2009 in Australia.
  • The number of new confirmed pandemic (H1N1) 2009 cases and hospitalisations has decreased nationally with a number of jurisdictions reporting no new notifications in the last week.
  • National influenza activity continues to decrease.
  • - ILI presentation rates to General Practitioners at a national level are below the baseline levels reached at the end of the 2007 and 2008 influenza seasons. In most jurisdictions ILI data have remained stable, however in some jurisdictions this is above background levels.
  • - ILI presentations to emergency departments have remained stable across reporting systems in Western Australian and South Australia this reporting period.
  • - Flutracking indicated that ILI activity remains at low levels in all States in the week ending 25 October 2009.
  • - Calls to the National Health Call Centre Network (NHCCN) regarding influenza-like illness continue to drop are and are at low levels.
  • - Absenteeism rates have remained stable in the last week and are at levels similar to those seen at the same time in 2007.
  • The number of respiratory tests positive for influenza A and pandemic (H1N1) 2009 are now very low. Type A influenza is the predominant seasonal influenza type reported by all jurisdictions and the pandemic strain has almost replaced the current seasonal H1N1 virus. Of the seasonal influenza A notifications, A/H3N2 is the predominant subtype reported by most jurisdictions.
    Top of page

    How severe is the disease?

  • Analysis of data to 23 October 2009a indicated that:
  • - The number of people with pandemic (H1N1) 2009 requiring hospitalisation continues to decrease. In total, 4,833 people have been hospitalised, with 13% admitted to Intensive Care Units. Of the hospitalisations for which Indigenous status is known, 803 (21%) have been Indigenous Australians. Pregnant women represent 27% of all hospitalisations for pandemic (H1N1) 2009 of women aged between 15 and 44 years.
  • - Of the number of deaths associated with pandemic (H1N1) 2009, 3 were pregnant women and 24 (13%) were Indigenous.
    Top of page

    Is the virus changing?

  • In Australia, 2 of 347 pandemic (H1N1) 2009 viral isolates tested by NA enzyme inhibition assay were resistant to oseltamivir and 4 of 145 clinical specimens tested positive for the H275Y mutation.
  • To date, the WHO has received formal notification of 39 cases of oseltamivir resistance pandemic (H1N1) 2009 viruses worldwide.
    Top of page

    International influenza surveillance

  • The number of human cases of pandemic (H1N1) 2009 is still increasing in many countries. As at 25 October 2009, the WHO Regional Offices have reported over 440,000 confirmed cases and over 5,700 deaths associated with pandemic (H1N1) 2009 worldwide.
  • In the temperate zone of the Northern Hemisphere, influenza like illness (ILI) activity continues to intensify marking an unusually early start to winter influenza season in some countries. In the temperate regions of the Southern Hemisphere influenza transmission has largely returned to baseline (Chile, Argentina, and New Zealand) or has declined substantially (Australia and South Africa).

    Top of page

    1. Influenza activity in Australia

    Laboratory Confirmed Cases

    There have been 18 new laboratory confirmed pandemic (H1N1) 2009 notifications in the last reporting week, with 3 jurisdictions reporting no new notifications. As of 30 October 2009 there were 37,141 confirmed cases of pandemic (H1N1) 2009 in Australia, including 187 associated deaths.

    Figure 1. Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 30 October 2009 by jurisdiction

    Figure 1. Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 30 October 2009 by jurisdiction

    Source: NetEPI database



    Figure 2. Influenza activity in Australia, by reporting week, years 2007, 2008 and 2009*

    Figure 2. Influenza activity in Australia, by reporting week, years 2007, 2008 and 2009

    * Data on pandemic (H1N1) 2009 cases is extracted from NetEPI; data on seasonal influenza is extracted from NNDSS.
    Sources: NNDSS and NetEPI databases




    Top of page

    Influenza Like Illness b

    Sentinel General Practice Surveillance

    Combined data available from the Australian Sentinel Practices Research Network (ASPREN), the Northern Territory GP surveillance system and VIDRL, up until 25 October 2009, show that nationally, influenza like Illness (ILI) consultation rates remained stable this reporting period and are below levels seen at the end of the 2007 and 2008 seasons (Figure 3). In the last week, the presentation rate to sentinel GPs in Australia was approximately 4 cases per 1,000 patients seen.

    Figure 3. Rate of ILI reported from GP ILI surveillance systems from 2007 to 25 October 2009 by week*

    Figure 3. Rate of ILI reported from GP ILI surveillance systems from 2007 to 25 October 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



    Further analysis of the ILI data during this period indicated that levels remained stable in most jurisdictions, however this is above background levels in some jurisdictions (Figure 4).

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week*


    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week western australia
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week australian capital territory
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week tasmania
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week queensland
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week victoria
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week south australia
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week new south wales
    Top of page

    Figure 4. Rate of ILI reported from ASPREN, VIDRL and NT by State from January 2009 to 25 October 2009 by week northern territory

    SOURCE: NT Surveillance[ </p>]

    *Care should be taken when interpreting graphs due to lags in reporting in some instances and small numbers being reported from jurisdictions. The last data point may be modified in future reports.




    Top of page

    Emergency departments

    ILI presentations to EDs continue have remained stable across reporting systems in Western Australian and South Australia this reporting period.
    Western Australia: the number of ILI presentations reported in EDs are elevated above baseline levels but have remained stable during this reporting period.
    South Australia: ILI presentations in EDs decreased from 13 presentations in the previous week to 11 presentations this reporting period. There were three admissions during this period, all as inpatients.2

    Top of page

    Flutracking

    Flutracking, a national online tool for collecting data on influenza-like illness, indicated that ILI activity remains at low levels in all States in the week ending 25 October 2009.

    Figure 5. Rate of influenza-like illness symptoms and absence from regular duties among Flutracking participants by week, from week ending 3 May 2009 to week ending 25 October 2009

    Figure 5. Rate of influenza-like illness symptoms and absence from regular duties among Flutracking participants by week, from week ending 3 May 2009 to week ending 25 October 2009

    Source: Flutracking Interim Weekly Report



    Top of page

    National Health Call Centre Network

    The number of calls regarding influenza-like illness to the National Health Call Centre Network (NHCCN) have continued to decrease, to 40 calls in the week ending 30 October 2009. The number of calls currently being received is low but not yet at pre-pandemic levels (Figure 6).

    Figure 6. Number of calls to the National Health Call Centre Network (NHCCN) regarding Influenza-like Illness, Australia, 1 January 2009 (Wk1) to 30 October 2009 (Wk44)

    Figure 6. Number of calls to the National Health Call Centre Network (NHCCN) regarding Influenza-like Illness, Australia, 1 January 2009 (Wk1) to 30 October 2009 (Wk44)

    SOURCE: NHCCN data



    Top of page

    Absenteeism

    The most recent available data indicates that in the week ending 21 October 2009, absenteeism rates continued to decrease. Absenteeism rates in recent weeks are similar to those seen at the same time in previous years (Figure 7).

    Figure 7. Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 21 October 2009, by week.

    Figure 7. Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 21 October 2009, by week

    SOURCE: Absenteeism data



    Top of page

    Sentinel Laboratory Surveillance - confirmed influenza notifications

    The number of respiratory tests positive for Influenza A and the number that are pandemic (H1N1) 2009 are now very low (Table 1).

    Table 1. Laboratory Respiratory tests that tested positive for influenza A and pandemic (H1N1) 2009

      ASPREN – national VIC NIC WA NIC NT (reported by WA NIC)
    Latest report        
    Number of specimens tested
    7
    6
    (at 1/11)
    177
    (at 31/10)
    0
    % tested which were Influenza A
    0
    0
    4
    0
    % tested which were pandemic (H1N1) 2009
    0
    0
    4
    0
    Previous report
    Number of specimens tested
    8
    5
    (at 25/10)
    197
    (at 25/10)
    n/a
    % tested which were Influenza A
    1
    0
    2
    0
    % tested which were pandemic (H1N1) 2009
    0
    0
    2
    0


    *ASPREN tests are collected every Tuesday. Results are reported for a rolling fortnight as data changes retrospectively.^VIDRL Influenza Report available from : http://www.vidrl.org.au/surveillance/flu%20reports/flurpt09/flu09.html



    From 1 January to 30 October 2009, type A is the predominant seasonal influenza type reported by all jurisdictions. Of the type A notifications for which there is subtyping information in NNDSS, the ratio of seasonal H1N1 to H3N2 is 1:2.3.


    Top of page

    2. Overview of pandemic (H1N1) 2009 severity - to 23 October 2009 c

    While pandemic (H1N1) 2009 is generally considered a mild disease at the community level, it has had serious consequences at the acute end of the disease. Figures of hospitalisations, ICU admissions and deaths are currently used as indicators to provide evidence on the severity of the disease in Australia (Table 2).

    Of particular note is the difference in the age distribution of the novel influenza virus to seasonal influenza and the increasing median age as the severity of the disease progresses: 21 years for all confirmed cases; 31 years for hospitalised cases; 45 years for ICU cases; and 54 years for deaths. The disease has also had a differential impact upon Indigenous Australians, who are ten times more likely to be hospitalised with the disease than non-Indigenous Australians. Pregnant women are also over-represented in the more severe cases with pregnancy being a risk factor in 27% of women aged 15 to 44 years who require hospitalisation for the disease.

    Table 2. Summary of severity indicators of pandemic (H1N1) in Australia, to 23 October 2009 c

      Confirmed pandemic (H1N1) 2009 cases Hospitalised cases ICU cases Deaths
    Total number
    37,149
    13% (4,833/37,149 confirmed cases)
    13% (650/4,833 hospitalisations)
    186
    Crude rate per 100,000 population
    173.1
    22.6
    3.2
    0.8
    Median age (years)
    21
    31
    45
    54
    Females
    51% (18,125/37,029)
    51% (2,455/4,833)
    53% (347/650)
    42% (78/186)
    Vulnerable groups (Indigenous, pregnant & individuals with at least 1 comorbidity)
    n/a
    57% (2,755/4,833)
    74% (484/650)
    67% (125/186)
    Indigenous people~
    11% (3,822/34,344)
    20% (803/3,908)
    20% (100/499)
    13% (24/186)
    Pregnant*
    n/a
    27% (278/1,030 hospitalised females aged
    15-44 years)
    17% (47/278 hospitalised pregnant women)
    4% (3/78 female deaths)
    Cases with at least 1 co-morbidity
    n/a
    49% (2,382/4,833)
    71% (460/650)
    65% (120/186)

    #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 is not always complete for each summarised figure.
    ~The denominator for this row is the number of confirmed cases for which Indigenous status is known.
    * Includes women in the post-partum period




    Top of page

    3. Virology

    Researchers in the US, have reported an oseltamivir-resistant pandemic (H1N1) 2009 virus infection has been passed from person-to-person during the US summer wave. The researchers have stated that this is the first of such cases and raises the possibility that widespread resistance will render the anti-viral drug, oseltamivir, less useful in combating the pandemic (H1N1) 2009 virus. Thus, the pandemic (H1N1) 2009 vaccine, instead of antivirals, should be used for prevention as it becomes available.3

    Top of page

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

    In 2009 up to 30 October 2009, 1,167 Australian influenza isolates have been subtyped by the WHO CC in Melbourne (Table 3). Of these, 621 influenza isolates have been antigenically characterized, with 62% Pandemic A/H1N1 2009 (A/California/7/2009-like).

    Table 3. Typing of Influenza isolates from the WHO Collaborating Centre, 1 January 2009 to 30 October 2009

    Antigenic characterization
    ACT NSW NT Qld SA Tas Vic WA TOTAL
    A(H1N1)
    2
    15
    0
    29
    18
    1
    11
    27
    103
    Pandemic (H1N1) 2009
    41
    64
    138
    75
    75
    9
    175
    190
    767
    A(H3N2)
    16
    95
    8
    41
    2
    8
    38
    68
    276
    B
    0
    8
    0
    1
    0
    0
    4
    8
    21
    Total
    59
    182
    146
    146
    95
    18
    228
    293
    1167

    i Composition of the 2009 Southern Hemisphere influenza vaccine
    SOURCE: WHO CC
    ii Recommended virus for Pandemic A(H1N1) 2009 vaccines
    iii Composition of the 2009-2010 Northern Hemisphere influenza vaccine
    Please note: There may be up to a months delay on reporting of samples
    Isolates tested by the WHO CC are not a random sample of all those in the community hence proportions of pandemic (H1N1) 2009 to seasonal are not representative of the proportions circulating. Early in the pandemic all influenza A untypeable samples were sent to the WHO CC for testing and later many pandemic (H1N1) 2009 positive samples were sent for confirmation, resulting in biases in the data.



    In general, seasonal influenza A strains circulating this influenza season are the same as strains in the vaccine, with the A(H3N2) virus drifting. Influenza B strains match more closely with those in the 2009-2010 Northern Hemisphere vaccine and may be drifting.


    Top of page

    Antiviral Resistance

    Pandemic (H1N1) 2009

    To date, the WHO has received formal notification of 39 cases of oseltamivir resistant pandemic (H1N1) 2009 viruses worldwide (Table 4).4 The isolates have a mutation in the neuraminidase that confers resistance to oseltamivir (referred to as H275Y), but they remain sensitive to zanamivir.

    Table 4. Worldwide oseltamivir resistant viruses

      Number
    Associated with the use of oseltamivir for post exposure prophylaxis 12
    Associated with the use of oseltamivir treatment in patients with severe immunosuppression 6
    Isolated from samples from patients receiving oseltamivir treatment 4
    Isolated from patients who were not taking oseltamivir for either treatment or prophylaxis. 2
    Unspecified 15
    Total 39

    The WHOCC in Melbourne has reported 2 isolates which tested resistant to oseltamivir by NA enzyme inhibition assay and 4 specimens with the H275Y mutation (Table 5).

    Table 5. Resistance testing of Australian pandemic (H1N1) 2009 viruses

      No. tested Resistant/positive for H275Ymutation
    Viral isolates tested in NA enzyme inhibition assay
    347
    2*
    Clinical specimens tested for the H275Y mutation known to confer resistance to oseltamivir
    145
    4

    *One virus was also identified to contain the H275Y mutation.



    Top of page

    Seasonal Influenza

    The last WHO report on resistance of seasonal strains to oseltamivir was released on 4 June 2009, during the Northern Hemisphere influenza season 2008-2009and stated that 96% of seasonal influenza A (H1N1) isolates tested from 36 countries worldwide were resistant to oseltamivir.5
    Table 6. Resistance Testing – Seasonal Influenza - Global

    Country Percentage of H1N1 viruses Percentage of A(H3N2) Percentage of B viruses
    Australia (since 1 January 2009)
    97.2% (36/37) resistant to oseltamivir
    0% (0/40) resistant to oseltamivir
    0% (0/6) resistant to oseltamivir
    New Zealand (up to 1 November 2009)6
    100% (53/53) resistant to oseltamivir
    n/a
    n/a
    US CDC (week ending 17 October) 7
    99.6% (1,146/1,151) resistant to oseltamivir
    100% (271/271) resistant to adamantanes
    n/a

    Top of page

    4. International Influenza Surveillance d

    As at 25 October 2009, the WHO Regional Offices reported over 440,000 confirmed cases and over 5,700 deaths associated with pandemic (H1N1) 2009 worldwide.8 The number of human cases of pandemic (H1N1) 2009 is still increasing in many countries.

    In the temperate zone of the Northern Hemisphere, influenza like illness (ILI) activity continues to intensify marking an unusually early start to winter influenza season in some countries. In the temperate regions of the Southern Hemisphere influenza transmission has largely returned to baseline (Chile, Argentina, and New Zealand) or has declined substantially (Australia and South Africa).

    Top of page

    Northern America

  • – the US, and parts of Western Canada continue to report high rates of influenza-like-illness (ILI) and numbers of pandemic H1N1 2009 virus detections;
  • The USA reported increased influenza activity during week 42 (October 18-24, 2009). Forty-eight states reported geographically widespread influenza activity, Guam and two states reported regional influenza activity, the District of Columbia and Puerto Rico reported local influenza activity, and the U.S. Virgin Islands did not report. 42.1% specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories positive for influenza. All subtyped influenza A viruses being reported to CDC were 2009 influenza A (H1N1) viruses. The proportion of deaths attributed to pneumonia and influenza (P&I) was above the epidemic threshold and twenty-two influenza-associated pediatric deaths were reported. Nineteen of these deaths were associated with 2009 influenza A (H1N1) virus infection and three were associated with an influenza A virus for which the subtype was undetermined. The proportion of outpatient visits for influenza-like illness (ILI) was above the national baseline and all 10 regions reported ILI above region-specific baseline levels.
  • Canada has reported widespread sharp increases in influenza activity across the country.
  • Mexico has reported more confirmed cases since September than during the springtime epidemic.

    Top of page

    Central and South America

  • - pandemic influenza transmission remains active in many parts of the tropical zone of the Americas, most notably in several Caribbean countries . 9
  • Cases of acute respiratory disease are decreasing in Central America and stable or decreasing in South America with the exception of Colombia, which reported an increasing trend for the seventh consecutive week. Barbados and Nicaragua have reported cases of co-infection of pandemic (H1N1) 2009 virus and dengue . 10
  • Swine flu has appeared among Venezuela's Yanomami Indians, one of the largest isolated indigenous groups in the Amazon, and a doctor said Wednesday that the virus is suspected in seven deaths, including six infants . 11

    Top of page

    Europe

  • - In Western Europe, high rates of ILI and proportions of respiratory specimens testing positive for pandemic H1N1 2009 have been observed in at least five countries: Iceland, Ireland, the UK (N. Ireland), Belgium, and the Netherlands. Many other countries in Europe and Western and Central Asia are showing evidence of early influenza transmission, including in Spain, Austria, parts of Northern Europe, Russia, and Turkey. [ <sup>12</sup>]
  • The influenza-like illness (ILI) rate in England from the Royal College of General Practitioners (RCGP) scheme increased to 42.8 per 100 000 in week 43, compared to 39.1 in week 42. An increase was seen in all age groups. The main burden of influenza-like-illness nationally is in the 1-4 and 5-14 years age groups. The Health Protection Agency (HPA) modelling gives an estimate of 78 000 new cases in England last week. This represents a 56% increase on the previous week . 13
  • There is continuing widespread influenza activity in Ireland, and activity increased markedly during week 43 . 14
  • The World Health Organization (WHO) is sending a team of experts to help the government of Ukraine where 2,300 people have been hospitalised with suspected pandemic (H1N1) 2009 virus infections and 60 people have died from respiratory problems in a week . 15

    Top of page
  • Asia

  • - Overall transmission continues to decline in most but not all parts of the tropical zone of South and Southeast Asia.
  • In Japan, influenza activity has also increased sharply, especially on the northern island, approximately 10 weeks ahead the usual start of the winter influenza season16
  • China’s pandemic (H1N1) 2009 virus cases are higher earlier than was expected and the number of cases are rapidly increasing. Health authorities have stated the epidemic could last until March next year.17

    Top of page

    Oceania

  • Influenza activity continues to decrease in New Zealand but the virus is still circulating, with consultations for ILI in the week ending 25 October 2009 at 27.7 consultations per 100,000 population.


    Top of page

    5. Pandemic (H1N1) 2009 virus in animals

    US officials have confirmed that the first case of pandemic (H1N1) 2009 virus has occurred in a cat. Two ferrets also contracted the pandemic (H1N1) 2009 virus, one in Oregon and the other in Nebraska and died from the illness . 18 The 2009 H1N1 influenza virus has now been found in humans, pigs, birds, and ferrets.

    Top of page

    6. 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.

    Top of page

    NetEpi

    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, WA, TAS and SA, and 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.

    Top of page

    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. NSW is also unable to send seasonal influenza notifications data.
    Top of page

    Data Analysis

    Analysis of confirmed cases in conducted on combined NetEpi and NNDSS data. Analysis of morbidity (hospitalisations and ICU admissions) and mortality data is conducted on combined NetEpi and QLD hospitalisation data.
    Top of page

    Laboratory Surveillance data

    Laboratory testing data are extracted from the ‘NSW Influenza Report,’ ‘The 2009 Victorian Influenza Vaccine Effectiveness Audit Report’ (VIDRL) and the ‘South Australian Seasonal Influenza Report’. These reports are provided weekly.
    Top of page

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

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

    Top of page

    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.

    Top of page

    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.

    Top of page

    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.

    Top of page

    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 season.

    Top of page

    Flutracking

    Flutracking is a simple online weekly survey, run by 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.

    Footnotes

    a. The data in this section of the report will be updated every four weeks and are based on data at 23 October 2009. The data will differ from the totals indicated throughout the rest of this report.


    b. 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


    c. The figures in this section of the report will be updated every four weeks and are based on data at 23 October 2009. These figures will differ from the totals indicated throughout the rest of this report.


    d. When possible, information in this section is collated from reports available within the current reporting period.




    Top of page

    7. References

    1. The Atlanta Journal-Constitution, HealthDay News report. http://www.ajc.com/health/content/shared-auto/healthnews/flu-/632578.html . Accessed 2 November 2009.
    2. South Australian Seasonal Influenza Report No.23. Available from:
    3. http://www.dh.sa.gov.au/pehs/notifiable-diseases-summary/flu-resp-intro.htm.
    4. The Atlanta Journal-Constitution, Health Day News report. http://www.ajc.com/health/content/shared-auto/healthnews/flu-/632578.html . Accessed 2 November 2009.
    5. WHO pandemic (H1N1) situation update #72. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 5 November.
    6. 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 5 November 2009.
    7. New Zealand Public Health Surveillance, Influenza Weekly Updates. Available at: www.surv.esr.cri.nz/virology/influenza_weekly_update.php . Accessed 5 November 2009.
    8. CDC Influenza reports http://www.cdc.gov/h1n1flu/pubs/ . Accessed 5 November 2009.
    9. WHO pandemic (H1N1) situation update #72. Available from http://www.who.int/csr/disease/swineflu/updates/en/index.html . Accessed 5 November.
    10. World Health Organization. Pandemic (H1N1) 2009 - update 72. http://www.who.int/csr/don/2009_10_30/en/index.html . Accessed 5 November 2009.
    11. Pan American Health Organisation, Regional Update. Pandemic (H1N1) 2009. (published on November 3, 2009), http://new.paho.org/hq/index.php?option=com_content&task=view&id=1973&Itemid=1167 . Accessed 5 November 2009.
    12. GPHIN Alert Email to Healthops, 5 November 2009. Accessed 5 November 2009.
    13. World Health Organization. Pandemic (H1N1) 2009 - update 72. http://www.who.int/csr/don/2009_10_30/en/index.html . Accessed 5 November 2009.
    14. UK Department of Health, Weekly swine flu update, 29 October 2009; http://www.dh.gov.uk/en/Publichealth/Flu/Swineflu/DH_107700 . Accessed 5 November 2009.
    15. Influenza Surveillance in Ireland - Weekly Update. Available from: www.hpsc.ie/hpsc/A-Z/EmergencyPlanning/AvianPandemicInfluenza/SwineInfluenza/Surveillance%20Reports/ . Accessed 5 November 2009.
    16. Centre for Infectious Disease Research and Policy: http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/nov0209ukraine-jw.html Accessed 5 November 2009.
    17. World Health Organization. Pandemic (H1N1) 2009 - update 72. Available from: http://www.who.int/csr/don/2009_10_30/en/index.html . Accessed 5 November 2009.
    18. Xinhua, 2 November 2009; http://news.xinhuanet.com/english/2009-11/02/content_12373438.htm . Accessed 5 November 2009.
    19. Associated Press Release: http://www.google.com/hostednews/ap/article/ALeqM5jr75crEkS7CYHpDahQAdaXRWCdbwD9BOU0900 . Accessed 5 November 2009. Accessed 5 November 2009.