Data centre and notes

The context in which this data is being collected and documented is unique. We are attempting to track in as timely a manner as possible an unfolding epidemic in which information is limited. Australia's federal system means separate jurisdictions take responsibility for healthcare and report it in different ways. At times, discretion and adaptation have been required. We've tried to document these below.

 

We are grateful to collaborators and especially readers for the many pieces of feedback and advice that have helped with information and decision-making. If you would like to send a comment or request, please get in touch.

 

Index
 

  1. Sources

  2. New daily cases versus net daily cases

  3. Confirmed cases and deaths

  4. Active cases and recoveries

  5. Transmission sources

  6. Testing

 

Sources


(Please see About page to read who collects, researches and collaborates on this data.)

 

 

New daily cases vs net daily cases

[Data downloads available]

Summary: The number of new cases each day may differ from the net number of cases added to the total. The Daily briefing on the homepage shows new cases and net added cases in brackets. e.g. 7(+4) = 7 new cases, but only 4 added to the total because 3 previous cases were removed. Epicurves on the site show new cases. For net cases, use the links below.

Several scenarios have led this site to track new daily cases and net daily cases separately. For example, cases are occasionally moved between jurisdictions to comply with national reporting standards that require reporting based on residency rather than locality. This causes cumulative totals to be adjusted upwards or downwards depending on whether the state or territory is sending or receiving the case/s. (In the past, they did not always announce these types of cases explicitly; they simply made adjustments to the running totals). Downward adjustments may also occur after cases have been ruled out following further investigation or false positive results. Another scenario that is increasingly frequent is the confirmation of 'historical' cases following serology testing. This is slightly different from the other situations because these cases do still represent new additions to Australia's case numbers, however they are not 'new' cases in an active sense. 

To help make sense of these daily announcements and adjustments, this site tracks new daily cases and net daily cases separately. The goal is to make sure we can see how many new 'active' cases there are, separately from historical cases or technical adjustments.

Other sites tracking COVID-19 cases in Australia usually track net cases added. i.e. Daily cases are calculated by subtracting yesterday's total from today's. Previously this site took that approach also, however it changed policy with respect to downward adjustments as of 15 April 2020, upward adjustments as of 12 May 2020 and newly confirmed 'historical' cases on 17 May 2020. These changes in policy have resulted in some retrospective changes to the epicurve which have been documented below via the charts that show the difference between new confirmed and net added cases.

While the main epicurve, which is on the homepage and states and territories page, shows new daily confirmed cases that are announced by states and territories, this collection of charts is designed to give the full picture of Australia's daily confirmed cases of COVID-19. Data is updated live and downloadable by clicking the download icon in the bottom left-hand corner of each chart. 

1. New daily confirmed cases (i.e. new confirmed cases as announced)
 
  • View and download national data here.​

  • View and download state and territory data here.

2.  Net daily added cases (i.e. cases added to reach announced total)
 
  • View and download national data here.​

  • View and download state and territory data here.​

 

3. Difference between new confirmed and net added cases
 

(Also shows revisions to the epicurve that come out of the changes in approach). 

  • View and download national data here.​

  • View and download state and territory data here.​

4. Cumulative total of confirmed cases
 
  • View and download national data here.​

  • View and download state and territory data here.​

 

Confirmed cases and deaths

  • Cases and deaths are recorded on the day they are announced or published to the public. This means cases recorded on today's date reflect the previous day's reporting period. Tasmania has generally reported in the evening cases from the current day, not the previous day. However from June 13 (following 0 active cases in Tasmania), this site now reports Tasmania's cases from the previous day, in line with other jurisdictions.

  • 2 Queenslanders who died in NSW are reported in Queensland figures.

  • At least 2 overseas tourists (non-residents) who died in Western Australia have been included.

  • 20 March 2020: NSW brought its reporting time forward, creating a lower than usual figure for that day. 

  • 6 April 2020: 1 Northern Territory case was removed due to double-count with NSW. (Action taken 1 May 2020).

  • There are ongoing discrepancies between the cumulative total number of confirmed cases as reported by individual states and territories compared with those reported by the federal government. This site currently reconciles with federal figures. The current and ongoing discrepancies are:

    • Northern Territory reports +1 (due to residency)

    • Tasmania reports -2 (due to residency)

    • NSW reports -189 (historic cases reported in crew members on board the Ruby Prince cruise ship. They were included on 3 July and for time series purposes assigned to 15 April. NSW Health did not add these cases to its reported total, issuing the following statement in a media release: 189 historic COVID-19 cases reported in crew members on board the Ruby Princess were reclassified as Australian cases and included in NSW totals reported by the Commonwealth Department of Health. These cases were reported as Australian cases to the World Health Organisation as part of the Australian Government’s international reporting obligations. The cases were reported by NSW Health at the time of diagnosis, but were not included in NSW totals as they were on board the ship and not in NSW when diagnosed. The cases were not associated with any further transmissions in Australia as they were managed on board the cruise ship. 

  • Running totals of confirmed cases may be adjusted upwards or downwards outside of announced confirmed cases. Please see the section above (new daily cases vs net daily cases) for details.

  • Interstate transfers: where a state announces 'new' cases but verbally specifies that some are 'old' due to interstate transfers, the old cases will not be added to the 'new' epicurve, but added only to the net daily additional cases. 

  • Historical cases following serology testing: where a state announces new historical cases following serology testing, these cases will not be added to the 'new' epicurve, but added only to the net daily additional cases.

  • 16 May 2020: 2 'historical' cases were confirmed in Western Australia. These were added to net daily cases, not new daily cases, however federal figures revised WA figures down by 1, therefore only 1 net case was added. 

  • 18 May 2020: The federal government added +3 net cases for both Victoria and Western Australia in order to reconcile cumulative totals. The originating dates of these cases are not clear, but based on previous downward adjustments that had caused the totals reported by the federal government to diverge from those reported by the states, the cases are likely to be: +2 on 12 May and +1 on 14 May for Victoria:, and +2 on 13 May and +1 on 16 May for Western Australia. Cases that had previously been removed from the net cases on these days have been reinstated.

  • 23 May 2020: Federal figures released by the Department of Health did not add new cases to Western Australia (+3) or Queensland (+2), leading to a total national figure of -5. This site generally reconciles with federal figures at the end of each day. Today however, federal figures are irreconcilable with remaining active cases in Western Australia and Queensland. Therefore this site currently reflects the totals as reported by the states, rather than the federal government. 

 

Active cases and recoveries

  • Before 5 April 2020, not all states and territories reported recoveries. The federal Department of Health began publishing recoveries on this date which created a jump for some jurisdictions.​​​

When does an active case become a recovery?

 

The answer varies across states and territories. 

  • The national guidelines for COVID-19 define conditions for release from isolation:

    • For asymptomatic cases, at least 10 days must pass without symptoms since the first positive test sample was taken;

    • For mild cases, at least 10 days must pass since the onset of symptoms, and there must have been no acute symptoms in the last 72 hours; and

    • There are further conditions for people who were hospitalised or will enter high-risk settings such as health care or residential age care facilities.

  • Spokespersons for ACT Health, Queensland Health, SA Health and WA Health all said recoveries are determined by public health officials who assess patient symptoms by interviewing the patient and make a determination based on the national guidelines. The Queensland Health website also refers to cases with a notification date of 30 days or more. A spokesperson for NT Health said a patient must return two consecutive negative test results.

  • NSW Health has published recoveries are assessed three weeks after the onset of illness by interviewing the case: cases reporting no symptoms are considered to have recovered and cases who have not recovered at three weeks are called in the following weeks until recovery. On 11 June 2020, NSW removed 104 active cases and published "Active cases are calculated as: total cases excluding persons recovered and lives lost. Cases that are not recorded as recovered or deceased after six weeks are not included.

  • Victoria Health and Tasmania Health have not responded to questions clarifying their processes. However, analysis makes it clear that Victoria allocates cases as 'recovered' approximately 10 days after test sample was taken (see the chart on the recoveries page that compares new cases with recoveries).

Inactive cases versus recoveries

  • Sometimes states classify cases as 'inactive' without formally classifying them as 'recovered', affecting the underlying calculation. This means the sum of active cases, recoveries and deaths does not necessarily reconcile with the total number of cases.

  • The reason why this is done is not always clear however:

    • In Victoria, a case appears to be removed from 'active' if it is not allocated to an LGA.

    • NSW has updated its definition of active cases. Previously, the state said cases were considered 'inactive' if the patient had not recovered or deceased after six weeks. On 25 June 2020, NSW Health published 'active cases are locally acquired COVID-19 cases with onset in the last four weeks. This is based on the date the person first developed symptoms.' Why would the patient not have been formally classified as recovered? It appears that NSW assesses patient-reported symptoms in order to establish a formal recovery. It is possible that these patients have not been contacted regarding symptoms, however the timing of their disease indicates the case is no longer active. 

  • ​Active cases movements have been:

    • NSW in particular has removed large numbers of active cases without formally classifying them: On 11 June 2020, NSW removed 104 active cases and published "Active cases are calculated as: total cases excluding persons recovered and lives lost. Cases that are not recorded as recovered or deceased after six weeks are not included. On 12 June 2020, NSW removed a further 149 active cases. On 25 June 2020, NSW removed removed a further 90 active cases.

    • Victoria: the sum of Victoria's reported recoveries, deaths and active cases does not always equal the total number of cases reported by that state. As of 22 May 2020, this site reflects Victoria's reported figures of recoveries and active cases separately despite this discrepancy.

    • Queensland: As of 4 June 2020, the sum of Queensland's reported recoveries, deaths and active cases does not equal the total number of cases reported by that state. The state has published ''Active' cases do not equal 'Total' cases less 'Deaths' less 'Recovered' cases, as information for some cases is still pending.' This site reflects Queensland's figures as reported.​

  • This site reflects state and territory figures with the following adjustments: 

    • As noted above, Tasmania reports -2 confirmed cases compared with federal figures. This site has included these cases in Tasmania's cumulative total (in order to reconcile with federal figures) but to date, has not included them in Tasmania's recoveries or active cases. This is in order to align with the figures Tasmania reports.

    • 2 deaths double-counted by Queensland and NSW (allocated to Queensland by this site and federal Department of Health) are being used by both states to calculate remaining active cases. The jurisdiction in which these people were originally counted as confirmed cases is unclear. This site reports the number of active cases as announced by each state.​

 

 

 

Transmission sources

  • Transmission sources come from a range of sources. NSW, Victoria, Western Australia and ACT provide time series data via data files or dashboards. Every other jurisdiction (including the Commonwealth) reveal transmission sources via press conferences, web pages or updates. There are two main differences between these sources: the date on which transmission sources are reported, and whether they retrospectively update earlier cases that have been reallocated. Daily updates are static representations of cases and transmission sources from which we can only capture what is announced on the day. Time series data are dynamic - they show cases according to notification dates and are updated retrospectively. Data NSW has confirmed cases are notified on the date of test sample taken. This has several impacts:

    • For those states that provide time series data (NSW, Victoria, WA and ACT), the daily announcements of transmission sources are accurate but do not necessarily match the dates in the official datasets.

    • The national view of transmission sources is a static display of cases that shows the developments in the past 24 hours. This includes allocation of new cases (which may or may not have been notified in that 24 hour period, depending on when the test sample was taken) and reallocation of older cases after further investigation. Therefore it will not necessarily show transmission sources on the same dates as the official data from NSW, Victoria, WA or ACT.

    • In general, this site ​reports information on the date it is announced or published, not the date on which a case is notified (which we do not always know). However, for transmission sources, this site now uses different approaches for different charts: 

      • The charts on the homepage are a direct reflection of announcements to the media and public. 

      • The charts on the page Transmission sources: national charts primarily source data from Commonwealth updates and are therefore static and based on announcement date.

      • The charts on the page Transmission sources: state and territory charts primarily source their respective data from the best possible source for that jurisdiction. For NSW, Victoria, WA and ACT, that is their time series data. (Caveat: as previously noted, cases are generally reported on this site against the date they were announced or published to the public, which means cases recorded on today's date refer to yesterday's reporting period. This creates confusion when case-line data (which has no delay) is placed alongside announcement-date data (which has one day's delay). Therefore, an artificial adjustment has been made in which the case-line data has been shifted forward by one day, to synchronise dates with the rest of the charts on this site).

      • Those jurisdictions that do not provide time series data have a different issue - it means that after a case is announced as 'under investigation' it is not often revisited for the sake of clarifying the transmission source to the public. This particularly occurs in Queensland. It affects the charts of daily transmission sources, but it's recommended you view the charts of cumulative totals on the transmission sources: state and territory charts page.

  • Charts go back as far as respective available data allow. This varies depending on the jurisdiction.

  • Negative values have been included in some charts to show movement between categories, but large removals of 'under investigation' cases have not always been included.

  • Transmission source updates are limited on weekends due to availability of data.

  • Notes re NSW data:

    • Why is NSW data delayed on some charts? Wherever possible, the official datasets (using case-line data) are preferred over data compiled from daily announcements / publications. However, publication of data in the NSW datasets may be delayed. NSW data says this is because the risk of gaining information about an individual in the dataset increases as the number of cases decreases.

    • 3 June 2020: there were changes made to the NSW dataset which saw cases shift by 1-2 days and some retrospective revisions.

    • 8 June 2020: NSW Health published "the source of 13 previously reported cases has been updated. These cases are known secondary and tertiary infections acquired from people infected overseas who were reported between 24 March and 11 April, and have therefore been reclassified from ‘acquired overseas’ to ‘locally acquired’ as part of ongoing data quality checks."

 

Testing

  • The Federal Department of Health has reported test numbers since 5 April 2020. Previously, data came from state and territory websites, dashboards, media releases and press conferences. Prior to 5 April, not all days were reported / captured for each jurisdiction. 

  • While the Federal Department of Health has reported this metric as 'tests done', it has become progressively clear that testing units have been reportedly inconsistently:

    • On 1 May 2020, Western Australia changed from reporting 'number of individuals tested' to 'number of tests completed'.

    • On 26 May 2020, NSW changed from reporting 'people tested' to 'tests performed' creating a significant rise on that day. The state provides this explanation about the tests that are included.

    • On 27 May 2020, a large jump in Victoria's reported tests indicates a similar change. 

  • There have been instances of bulk removals or additions to testing totals: 

    • ​On 8 June 2020, Victoria removed 12,142 duplicate negative tests.

    • On 22 June 2020, Queensland reported an additional 38,500 retrospective tests, which were conducted by a private pathology provider.

 
 
 
 
 
 

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