Life expectancy at birth in Australia dropped slightly (by around 0.1-0.2 years to 83.2 at birth),  in the latest calculation from the ABS. That’s not surprising. Mostly due to Covid-19 deaths, mortality was worse in 2022 and 2023 than in the 2010s.

The life expectancy number (despite its name) is a way of summarising all of the mortality rates in a population at a point in time. In this case, the point in time is 2021-2023, which for Australia, was the period where Covid-19 had the biggest impact on mortality. In 2022, Covid-19 ripped through the population, and was the third highest cause of death. In 2023, it was still the ninth highest cause of death, and Covid-19 caused more than ten times the number of deaths as influenza.

What does life expectancy mean?

Life expectancy, as a calculation, is the average years someone will live from now if they experience a given set of mortality rates. To calculate it, you take a hypothetical population of people at age 0 (or another age), and apply the age based mortality rates for each year, until there is no-one left. Then you take the total years lived by all those people, and divide it by the number of people you started with, to get the average number of years someone will live from birth (or another age), given those mortality rates.

So it can be calculated using any set of mortality rates, but it is normally calculated using the mortality rates experienced by the population right now. But nobody actually experiences today’s mortality throughout their lives. Mortality rates are always changing, so a baby born today is unlikely to experience the same mortality at age 20 as a 20 year old does today.

For a personal example, here’s a little something I wrote for my dad years ago. When he was born in 1933, his life expectancy (calculated at the time using mortality rates then) was 63 years. But his life expectancy calculated using mortality rates that actually occurred during his lifetime would have been 70 years (if an actuary in 1933 could have exactly predicted the future).

So what does the decline in life expectancy tell us?

Life expectancy is a very quick summary of the overall mortality in a population. So the fact that Australia’s life expectancy declined in the most recent statistics tells you that Australians overall were slightly more likely to die (at a given age) in the 2021-2023 years than they had been previously. More than 15,000 people died in Australia from Covid-19 during that period. While some of them would have died of other causes, most of those people would have still been alive had Covid-19 not occurred. The Actuaries Institute estimated that there were over 30,000 excess deaths during those three years – deaths were 6% higher than expected, not just from Covid-19, but from other (probably related) causes.

Will life expectancy continue to go down now?

While Covid-19 continues to be an additional cause of death, it doesnt seem to be getting worse than 2022-23. So my expectation is that we will return to gradually improving mortality, but from this worse base level.