Excess Deaths in Australia: Frequently Asked Questions


13 December 2023

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Statistics and Mapping

Contents

Introduction
What is excess mortality?
Why track excess mortality?
What data is used to estimate excess deaths?
How are the ‘expected’ and the ‘unexpected’ or ‘excess’ deaths calculated?
How many excess deaths occurred in Australia in 2022?
What were the main causes of the excess deaths in Australia in 2022?
What effects will the pandemic have on mortality in the future?
Further information

 

Introduction

In Australia excess mortality or ‘excess deaths’ are the difference between the number of deaths from all-causes compared to the number of ‘expected’ deaths.

In 2022 there were an estimated 18,600 to 20,200 more deaths (‘excess deaths’) than might have occurred in the absence of the COVID-19 pandemic. More than half of these deaths were from COVID-19, but the greater than expected number of deaths from cancer, dementia, diabetes, and heart disease highlight some of the pressures the pandemic placed on our health and care systems.

Preliminary mortality figures for the first few months in 2023 show Australia is still experiencing excess deaths. Monitoring the gap between expected and actual deaths can provide early indications of the people and institutions most at risk in an emergency (such as the COVID-19 pandemic) and support better targeting of interventions and resources.

What is excess mortality?

In Australia, reported excess mortality is the deaths from all diagnosed causes (including COVID-19) which are greater than might be expected when compared with a modelled estimate based on recent historical experience.

The World Health Organization (WHO) defines excess deaths as:

Excess mortality is defined as the difference between the total number of deaths estimated for a specific place and given time period and the number that would have been expected in the absence of a crisis (e.g., COVID-19 pandemic). This difference is assumed to include deaths attributable directly to COVID‑19 as well as deaths indirectly associated with COVID-19 through impacts on health systems and society, minus any deaths that would have occurred under normal circumstances but were averted due to pandemic-related changes in social conditions and personal behaviours.

Why track excess mortality?

Excess mortality can show the extent an event (such as a pandemic or a natural disaster) is affecting the population.

Australia’s health and vital statistics systems allow accurate and relatively timely reporting of COVID-19 cases and deaths. During the early days of the pandemic, there were few (if any) deaths from COVID-19 in Australia where COVID-19 was not recorded on the death certificate. This is not the case for all countries monitored by the WHO,[1] where excess deaths may be a proxy for COVID-19 deaths due to insufficient COVID-19 testing and/or diagnosis guidelines.

Analysing the difference between actual and expected deaths can offer early indications of:

  • the health risks and social effects of having high numbers of infectious diseases circulating, and
  • areas where health systems may be under additional short or long-term stress, with potential flow on effects on the health of the population and the ability of our health systems to respond to changing health needs.

The WHO (2022) Q&A on Global excess deaths associated with the COVID-19 pandemic notes:

Deaths directly attributable to COVID-19 provide only a narrow perspective of the wide ranging harms being caused by the pandemic. The collateral damage from COVID-19 is much wider. It is important to quantify this now as it can inform choices that governments must make regarding prioritization between routine and emergency health systems.

The WHO also note that ‘excess mortality estimates go beyond estimation of the impact of the COVID-19 pandemic’ and support decision makers in ‘better targeting of interventions and resources to those most in need to prevent future deaths’ and in preparing for future pandemics.

For example, in Australia, the very low rates of death from influenza and other respiratory diseases (fewer than ‘expected’ deaths) in 2020 may provide evidence of the effectiveness of the public health interventions introduced to limit the spread of COVID-19 (for example, the restrictions on public gatherings and movement including limiting numbers at venues, working from home, and border closures), as the restriction periods correlate to lower infection rates of other airborne viruses.

What data is used to estimate excess deaths?

Australian Bureau of Statistics (ABS) – Deaths

Within months of the first recorded cases of COVID-19 in Australia, the ABS began reporting Provisional Mortality Statistics, to provide more timely information on mortality patterns during the pandemic. This data, along with detailed data on recent deaths and reliable population estimates by age, can offer insights into what deaths might be expected under usual circumstances.

The official mortality figures for 2022 will be released in the annual ABS Deaths and Causes of Death datasets (published later in 2023). Revised causes of death data for 2021 was released in April 2023.

How are the ‘expected’ and the ‘unexpected’ or ‘excess’ deaths calculated?

There is no ’standard’ way of estimating the expected number of deaths used to calculate excess deaths which is why there are various estimates of excess deaths for a given country over a given period.

ABS baseline estimates from historical averages

The ABS  Provisional Mortality Statistics for January to December 2022 reports a baseline estimate of ‘expected deaths’ by taking the average (mean) number of weekly deaths occurring in 2017–2019 and 2021. Data from 2020 is not included in this baseline because the number of deaths was significantly lower than expected, especially during winter.[2]

These baseline estimates can be used as a proxy for the expected number of deaths, an indicator of higher or lower expected mortality. The ABS Provisional Mortality Statistics baseline for 2022 includes data recorded during the COVID-19 pandemic (2021) and is not adjusted for population size and age structure.

The ABS explicitly states the Provisional mortality publication estimates should not be used as official excess mortality estimates. These figures are not adjusted for changes in age structure which may overestimate excess deaths, as an older population can expect increasing numbers of deaths relative to its population size.

In the article Measuring Australia's excess mortality during the COVID-19 pandemic until the first quarter 2023 the ABS have modelled the number of expected deaths (in the absence of the pandemic or an epidemic) based on a model developed for identifying excess deaths from influenza (see Table 1). This model uses the average number of deaths in the same weeks in 2013 to 2019 to create a baseline measure with upper and lower bounds, but it smooths out the ‘outliers’ or high number of deaths from the 2017 influenza epidemic to work out whether the variation is falling outside the probable variation in deaths in any given week in the absence of an epidemic.  Estimates are age-adjusted to account for differences in the age composition of the population.

Actuarial estimates: Australian Actuaries Institute

Actuaries evaluate risks (including the risk of death) by applying mathematical, statistical, economic, and financial analyses to business problems in the insurance, superannuation, health financing, and other fields.

Actuaries from the (non-government) Australian Actuaries Institute have formed a COVID-19 Mortality Working Group which produces  an analysis of excess mortality, using the ABS provisional mortality data.

The COVID-19 Mortality Working Group analysis uses a 2015-19 expected deaths baseline and adjusts for population size and ageing (unlike the ABS provisional deaths baseline).

This analysis gives a lower estimate for 2022 than the ABS provisional estimates but a higher estimate than the ABS modelled estimates (using different assumptions), as shown in Table 1.

How many excess deaths occurred in Australia in 2022?

Media and broader public discussion of ‘excess deaths’ followed the ABS publication of provisional mortality data for the six months to June 2022 which indicated there had been 17% more deaths than in previous years (based on a four-year historical average (2017-19 and 2021)).

The actuarial estimates of excess mortality for the same six months estimated 13% more deaths than expected (based on a 2015-19 average adjusted for population size and ageing) and offered additional insights into how the pandemic was affecting mortality and which people and institutions were most at risk. Table 1 shows the different estimates for the first 6 months of 2022, and all of 2022.

Table 1. Estimates of ‘excess’ mortality by time period and modelling assumptions

Estimates of expected deaths based on historical averages only Estimates of expected deaths in the absence of COVID-19
ABS Provisional mortality Statistics Actuarial analysis by the COVID-19 Mortality Working Group ABS Measuring Australia's excess mortality during the COVID-19 pandemic
January to June 2022 13,524 (17.1%) 11,200 (13%) no estimate
January to December 2022 25,235 (15.3%) 20,200 (12%) 18,634 (10.9%)
January to March 2023 4,451 (11.8%)  2,300 (6%) 3.280 (9.1%)

Sources: Australian Bureau of Statistics Provisional Mortality Statistics (various releases) COVID-19 Mortality Working Group COVID 19 Blog

Australian Bureau of Statistics, Measuring Australia's Excess Mortality During the COVID-19 Pandemic Until the First Quarter 2023,  Excess mortality, Australia and by state, Jan 2013 – Mar 2023 (data download), (Canberra: ABS, 2023)

The ABS article Measuring Australia's excess mortality during the COVID-19 pandemic until the first quarter 2023 (published in July 2023) offers an estimate of excess deaths for all of 2022.  Like the COVID-19 Mortality Working Group, this ABS analysis uses baseline data prior to the COVID-19 pandemic but incorporates different methodological assumptions. This analysis suggests excess mortality in 2022 was just under 11% (10.9% as shown in Table 1).

Table 2 taken from the same ABS analysis shows the effects of the pandemic have varied across Australian states and indicates COVID-19 is still having an effect on mortality in the first quarter of 2023.

Table 2. Excess mortality as a percentage above expected by jurisdiction, 2020-23

  2020 2021 2022 Jan -Mar 2023
Australia -3.1 1.4 10.9 9.1
New South Wales -4.1 0.1 10.7 8.6
Victoria -0.9 3.4 13.2 12.0
Queensland -4.3 0.8 10.1 7.8
South Australia -3.2 0.5 9.2 8.9
Western Australia -3.9 0.6 6.2 6.1
Tasmania -3.6 5.8 13.6 17.3
Northern Territory 1.5 6.8 10.6 np
Australian Capital Territory -4.3 -2.8 12.1 8.9

Source: Australian Bureau of Statistics, Measuring Australia's Excess Mortality During the COVID-19 Pandemic Until the First Quarter 2023, (Canberra: ABS, 2023)

Notes: Data is provisional and subject to change. Years are based on a sum of ISO weeks derived from the weekly modelling. There are 53 weeks in 2020. There are 52 weeks in 2021 and 2022. Excess mortality has been estimated for the first 12 weeks of 2023, np = not published. Deaths in 2023 are deaths that occurred by 26 March and were registered and received by the ABS by 31 May 2023.

 

What were the main causes of the excess deaths in Australia in 2022?

The Provisional Mortality Statistics reports on selected causes of death by underlying cause for doctor-certified deaths. The underlying cause of death is ‘the disease or injury that initiated the train of morbid events leading directly to death’, with other causes recorded on the death certificate seen as contributing to the death. Table 3 shows provisional 2022 data for common causes of doctor certified deaths, including COVID-19, and the baseline averages for the same diseases. The difference between the two is indicative of a changing pattern of mortality and not an estimate of excess deaths.

Table 3. Doctor certified deaths, selected causes of death, January to December 2022

  2022 2022: Baseline average Difference between certified deaths and baseline estimate
Cancer 50,314 47,614 2,700
Dementia 16,909 14,680 2,229
Respiratory diseases 14,377 14,146 231
 Chronic lower respiratory diseases 8,013 7,719 294
 Influenza and pneumonia 2,614 3,024 -410
Ischaemic heart disease 14,930 14,545 385
COVID-19 9,732 n.a. .. 
Cerebrovascular diseases 9,296 9,515 -219
Diabetes 5,598 4,698 900

Source: Australian Bureau of Statistics, Provisional Mortality Statistics, January to December, 2022, (Canberra: ABS, 2023) with additional work by the Parliamentary Library.

Notes: Only doctor-certified deaths are included. Data is by date of death (occurrence). The baseline includes deaths from 2017-19 and 2021, averaged to remove year on year fluctuations in death numbers. COVID-19 deaths are not included in the baseline as only one year of data is available. As the baseline includes 2021 data it is not measuring excess mortality in the absence of the COVID-19 pandemic. Other estimates of excess mortality should be used for this purpose.

In a 2023 online article, Confirmation of 20,000 excess deaths for 2022 in Australia, the COVID-19 Mortality Working Group estimate COVID-19 infection was the most common cause of excess deaths in Australia in 2022. The analysis estimates deaths from COVID-19 (10,300 deaths) represent just over half of all excess deaths and there were another 2,900 excess deaths where COVID-19 was a contributing factor.

For the excess deaths in 2022 where COVID-19 was not the underlying or a contributing cause, the working group considered the mostly likely reasons to be:

  • The impact of [having had] COVID-19 on subsequent mortality risk, particularly heart disease, stroke, diabetes and dementia, which have all been identified in studies
  • Delays in emergency care, particularly at times of high prevalence of COVID-19 and/or influenza, and
  • Delays in routine care, which refers to missed opportunities to diagnose or treat non-COVID-19 diseases and the likelihood of consequent higher mortality from those conditions in future.

The analysis also reports correlations that may help to identify the drivers of mortality changes, noting:

  • deaths with COVID-19 have followed the same pattern as deaths from COVID-19 in 2022
  • non-COVID-19 excess deaths have been highest when there have been peaks in COVID-19 deaths and peaks in influenza deaths
  • deaths due to some causes (dementia in particular) are closely correlated to the level of respiratory disease (including COVID-19) circulating
  • non-COVID-19 excess deaths are less apparent when there is no or little COVID-19 circulating, as illustrated by the difference between Western Australia and the other states in early 2022.

What effects will the pandemic have on mortality in the future?

On 5 May 2023 the WHO determined ‘that COVID-19 is now an established and ongoing health issue which no longer constitutes a public health emergency of international concern’. However, it also noted ‘SARS-CoV-2 is expected to continue circulating for the foreseeable future’ and urged governments to maintain and strengthen systems for surveillance.

Recent Australian case numbers and deaths suggest the effects of COVID-19 will continue into 2024. The ABS have reported that from March 2020 to June 2023:

  • 18,922 deaths[3] where people died with or from COVID-19
  • The underlying cause of death for 14,941 (79.0%) of these people was COVID-19
  • There were a further 3,981 people who died of other causes (e.g., cancer) but COVID-19 contributed to their death
  • Chronic cardiac conditions were the most common pre-existing chronic condition for those who had COVID-19 certified as the underlying cause of death.

Using updated data and modelling for 2023, the COVID-19 Mortality Working Group report that excess mortality in the first 6 months of 2023 was mainly due to COVID-19. There were 5,500 more deaths than would have been expected without the pandemic, and more than half of these were deaths from COVID-19.

The actuarial analysis reported in the article Counting the toll of COVID notes the prevalence and severity of future COVID-19 strains will affect the number of COVID-19 deaths. However, it is not clear what the other longer-term effects of the pandemic on mortality will be. It notes future mortality rates may also change due to the longer-term effects on people’s health of having delayed medical care in 2021 and 2022, as well as the effects of having been ill with COVID-19.

Further information

Australian data and resources on COVID-19 and excess deaths

Actuarial analysis

Statistics

Australian Bureau of Statistics (ABS)

Australian Institute of Health and Welfare, Australia’s health 2022 data insights, 7 July 2022

International data and resources on COVID-19 and excess deaths

World Health Organization

Our World in Data

National Center for Health Statistics (USA) (updated monthly) Excess Deaths Associated with COVID-19 - Provisional Death Counts for Coronavirus Disease (COVID-19)

Office of National Statistics (United Kingdom)

The Economist, Tracking COVID-19 excess deaths across countries, 20 October 2021

 

[1] See for example https://www.who.int/data/sets/global-excess-deaths-associated-with-covid-19-modelled-estimates

[2] See ABS (2023) Provisional Mortality Statistics methodology Baselines and average numbers. Unlike the situation in Australia, the UK Office of National Statistics 2022 baseline excludes 2020 deaths due to high numbers of COVID deaths – see Office for National Statistics (12 January 2022) Understanding excess deaths during a pandemic. This allows ‘… deaths in 2022 to be compared with a five-year average that is as up to date as possible while still being close to representing a ‘normal’ year.’

[3] Deaths that occurred by 30 June 2023 and have been registered and received by the ABS.

 

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