4.4 Mortality Te mate

4.4 Mortality | Te mate

While there were few deaths in New Zealand from COVID-19 during 2020 and 2021, in 2022 death rates approached those of other countries.

4.4.1 Counting COVID-19 deaths | Te tatau i ngā mate KOWHEORI-19

It is not always possible to be clear about the cause of death, particularly in cases where there are co-morbidities. Respiratory infections such as COVID-19 can trigger other life-threatening events, such as heart failure or stroke. And other health issues may make individuals more susceptible to respiratory infections.

Because of this we present data on weekly COVID-19 deaths in New Zealand using two different measures. The orange line in Figure 19 shows the number of deaths that were directly attributed to COVID-19 by medical staff. The blue line shows the number of deaths within 28 days of the person being reported as a COVID-19 case. This will include cases where the individual died of a health issue that has been induced or magnified by the virus. It will, however, also include cases where death was unrelated to COVID-19. Both measures are subject to reporting and classification issues. That said, it is likely that the actual number of deaths caused by COVID-19 lies between the orange and green lines.

Figure 19: Weekly COVID-19 deaths in New Zealand, 2020–2023

Source: Ministry of Health, 'New Zealand COVID-19 Data', https://github.com/minhealthnz/nz-covid-data, from Mortality Collection (cause of death) and NHI database (date of death)
Notes:
1. Deaths attributable to COVID-19 are those where COVID-19 is recorded as either the underlying cause of death or a contributory cause of death, according to World Health Organization guidelines.
2. Deaths within 28 days of being reported as a case also includes people who died within 28 days of being reported as a case, but had a cause of death unrelated to COVID-19.¹⁰ Health New Zealand stopped reporting deaths within 28 days on 16 October 2025.¹¹

We can see how this translates into total deaths in Figure 20. The differences between the two measures add up over time creating a wider disparity. Nevertheless, the total number of deaths from COVID-19 by the end of the 2023 is likely to have been between four and five thousand people, equating to around one in 1,000 New Zealanders.

Figure 20: Cumulative COVID-19 deaths in New Zealand, 2020–2023

Source: Ministry of Health, 'New Zealand COVID-19 Data', https://github.com/minhealthnz/nz-covid-data

To place these numbers in context, we need to understand how they compare to the overall number of deaths that occur in New Zealand. Figure 21 shows deaths from 1980 to 2025. The data are presented quarterly, so we can see the clear seasonality to patterns of mortality as deaths are more common in winter months.

Figure 21: Deaths from all causes in New Zealand

Monthly deaths with trend line, January 1980 to March 2025

Source: Stats NZ, 'Deaths – VSD, Month and year of death (Monthly)', https://infoshare.stats.govt.nz/SelectVariables.aspx?pxID=e3761960-d694-46f2-990e-9dffe04d0142
Notes:
1. Deaths data are based on deaths registered in New Zealand to people resident in New Zealand by date of death (not date of registration). Data from 1990 are subject to revision.
2. Data have been randomly rounded to protect confidentiality.
3. Individual numbers may not add up to totals, and values for the same data may vary in different tables

There has been a gradual increase in the death rate since the early 1990s due to the ageing population. Older people are more susceptible to illness, including respiratory illness. If we focus on the seasonal pattern, we can see that 2020 was unique as we did not see the usual spike in winter months due to seasonal flu. Measures taken to reduce the spread of COVID 19 also affected the spread of other respiratory infections. We look at this issue in more detail in section 5.3.2.

That said, older New Zealanders are living longer lives. New Zealand – like many high- and middle-income countries – has experienced a steady decline in the age-adjusted mortality rate over the past half century.¹²

4.4.2 Excess mortality | Te mate nui ake i te paerewa

Because of the complications in collecting, using and interpreting death data during a pandemic,¹³ an alternate measure used by epidemiologists is excess mortality. Excess mortality refers to the additional number of deaths, from all causes, during a crisis, above the level we would expect to see in 'normal' times.¹⁴ Excess mortality is a more comprehensive measure of the total mortality impact of the COVID-19 pandemic because it captures not only confirmed deaths (as in earlier figures), but also COVID-19 deaths that were not accurately diagnosed and reported. In addition, excess mortality captures non-COVID-19 deaths attributable to the disruption caused by the pandemic, along with deaths avoided because of  the pandemic, such as reduced road deaths during lockdowns.

There are several ways to calculate excess mortality, all of which compare actual deaths during a period with an estimate of the number of deaths that might have been expected in that period, given trends in previous years (for example, more in winter than in summer, an ageing population).

We use excess mortality data from the World Mortality Database supplied by Our World in Data.¹⁵ Using this dataset, we find that by the end of 2022, New Zealand was one of only five jurisdictions that experienced fewer deaths than one would expect in a normal, non-pandemic year (that is, negative excess mortality) (Figure 22). The other jurisdictions with negative excess mortality were Bhutan, Greenland, Japan and Taiwan.

Figure 22: Excess mortality by country, 2020–2022

Source: Human Mortality Database; World Mortality Dataset (2024); Karlinsky and Kobak (2021) and other sources, processed by Our World in Data

This situation changed in 2023. New Zealand's cumulative excess mortality (over the period 2020–2023) became slightly positive, with the number of deaths 0.36% higher than would be expected if there was no pandemic. This was the sixth lowest of the 89 jurisdictions in the Our World in Data dataset (Figure 23). In our group of comparator countries (identified in the Figure), Japan had the next lowest cumulative excess mortality (3.6%), followed by Australia (5.58%) and Sweden (5.64%). Italy, the United Kingdom and the United States had excess mortality rates that were 9% or more higher than would be expected if there was no pandemic.

Figure 23: Excess mortality by country, 2020–2023

Source: Human Mortality Database; World Mortality Dataset (2024); Karlinsky and Kobak (2021) and other sources, processed by Our World in Data.
Notes: Excess mortality: Cumulative deaths from all causes, 2020–2023, compared with projection from previous years.

4.4.3 Updated excess mortality for New Zealand | Te mate nui ake i te paerewa kua whakahōungia mō Aotearoa

In 2025 Plank, Senanayake and Lyon modelled excess mortality in New Zealand to account for age, sex and seasonality.¹⁶ Their results are presented in Figure 24. They also show a period in 2020 where mortality was less than normal (that is excess mortality was negative). Figure 24 shows a slightly different story to the World Mortality Data/Karlinsky and Kobal (2021) method used in Figures 22 and 23 for 2021, in which excess mortality is much closer to zero.

The study shows that excess deaths became positive and followed a similar pattern to COVID-19 deaths in 2022 and early 2023. The authors note that the magnitude, timing, and age-distribution of the excess closely matched those of COVID-19-attributed deaths. They interpret this as suggesting that the bulk of the excess mortality in 2022–2023 was directly attributable to COVID-19, either as an underlying or a contributory cause of death. They suggest this could be because there were relatively few COVID-19 deaths that were not recorded as such. They also note that any undocumented COVID-19 deaths may have been offset by reduced mortality from other causes, such as other (non-COVID-19) respiratory diseases. We return to this in section 5.3.2 below.

Figure 24: Modelled excess mortality in New Zealand, 2020–2023

Excess mortality estimates and recorded deaths attributed to COVID-19, monthly

Line graph showing monthly deaths from 2020-2023. Shows two lines - green line for COVID-19 deaths and orange line with dashed confidence intervals for excess deaths. Y-axis shows "Monthly deaths" ranging from -600 to 600. Notable features include a significant dip to around -600 in 2020, followed by fluctuations and peaks reaching around 600 deaths in 2022-2023.

Source: Michael J. Plank, Pubudu Senanayake and Richard Lyon, 'Estimating excess mortality during the Covid-19 pandemic in Aotearoa New Zealand: Addendum', arXiv preprint arXiv:2512.02266, update of original article in International Journal of Epidemiology, Volume 54, Issue 4 (2025).

Notes: Monthly COVID-19-attributed deaths (blue line) along with excess deaths according to Plank and others' QPR model (orange line and open circles). Error bars show the 95% confidence interval for the QPR model.

¹⁰ Ministry of Health, 'Covid-19 deaths reporting update', 18 May 2022, https://www.sunlive.co.nz/news/294135-covid19-deaths-reporting-update.html

¹¹ Health New Zealand Te Whatu Ora, 'COVID-19 reporting changes', last updated 24 November 2025,

¹² Health New Zealand I Te Whatu Ora, 'Mortality data web tool', https://tewhatuora.shinyapps.io/mortality-web-tool/

¹³ Francisco Checchi and Les Roberts, 'Interpreting and using mortality data in humanitarian emergencies', Humanitarian Practice Network, 52 (2005).

¹⁴ Edouard Mathieu and others, 'Excess mortality during the Coronavirus pandemic (COVID-19)', 2020, https://ourworldindata.org/excess-mortality-covid

¹⁵ Ariel Karlinsky and Dmitry Kobak, 'Tracking excess mortality across countries during the COVID-19 pandemic with the World Mortality Dataset', eLife, 10 (2021), https://doi.org/10.7554/eLife.69336

¹⁶ Michael J. Plank, Pubudu Senanayake and Richard Lyon, 'Estimating excess mortality during the Covid-19 pandemic in Aotearoa New Zealand', International Journal of Epidemiology, Volume 54, Issue 4, (2025)