The Australian Bureau of Statistics this week released a provisional tally of the changes in Australia’s overall death rate amid the coronavirus epidemic.
The figures record 33,066 doctor-certified deaths in Australia from January 1 to March 31, 2020 – compared with an average of 32,249 during the corresponding months during the years 2015-19.
What’s more, the final week of March 2020 featured the highest weekly death rate of the entire three-month period, with 2,649 recorded deaths. That week also featured the highest numbers of deaths from respiratory diseases, diabetes and dementia.
Australia has had 103 known COVID-19-related deaths, with 21 reported before the end of March. The ABS death counts for respiratory diseases do not include these known cases, but might include COVID-19 deaths that were not recognised or confirmed as such at the time.
Overall, there were more than 800 “excess deaths” in the first quarter of 2020, compared with the average of the previous five years. The 103 confirmed COVID-19 deaths represent just a small fraction of these deaths. But my analysis shows that even in the early days of the pandemic, there are some signs that the impact of COVID-19 on Australia’s death rate may be bigger than the official tally suggests.
Death data allow us to monitor death rates by age, gender, location and cause, and to assess how death rates are changing over time. “Excess deaths” – those that exceed the long-term average – are particularly important to understand, not least during a pandemic but also because they could be due to preventable causes.
The coronavirus death toll has become a feature of media coverage during the COVID-19 outbreak. Unlike in many other countries, the epidemic has stayed within the capacity of Australia’s health system, so we might reasonably expect all COVID-19-related deaths to have been counted accurately.
However, analysis of sewage and swab samples in Europe suggest SARS-CoV-2 (the coronavirus that causes COVID-19) may have been responsible for infections as early as December, before the world became aware of the emerging crisis in Wuhan.
Given the uncertainty about when the coronavirus actually entered Australia, it is possible Australia had COVID-19 cases before official counts began. If so, they may have been recorded as a death from another cause in the death register, most likely as pneumonia.
A death can only be officially attributed to COVID-19 if that patient had been tested for the coronavirus. Australia had a limited supply of test kits initially, and the rules for testing were strict in the early days, mainly focused on returned travellers and their immediate contacts. Testing rules did include hospitalised patients with community-acquired pneumonia, but this recommendation may not always have been followed.
What do the new data show?
The newly released ABS data are raw counts that only include deaths which occurred in January-March and were registered by the end of April. On average, 98% of deaths are reported to the ABS by the end of the following month.
The data compare the weekly death rates against the five-year average death counts for those same weeks from 2015 to 2019. There has been some population growth over this time, which in itself might lead to a rise in expected deaths, but is not yet factored in here. These counts only relate to the deaths that a doctor has certified (in home or hospital), but this is likely to include most deaths directly associated with COVID-19 patients, diagnosed or not.
The 33,066 recorded deaths in the first three months of 2020 is well above the five-year average of 32,249. But overall, the 2020 deaths follow a similar pattern to previous years, with the count rising as we enter the cooler months.
Authors: Catherine Bennett, Chair in Epidemiology, Deakin University