This comes as life expectancy has dropped by more than two years in the United States.

The study from the Australian National University (ANU) discovered the life expectancy of Australians jumped in 2020. Instead of the expected 0.09 to 0.14 years' average annual increase in longevity seen from 2015 to 2019, researchers found a surge to 0.7 years' increase from 2019 to 2020 for both females and males. This was the greatest increase of all the countries looked at in the study, published in the International Journal of Epidemiology.

The countries with the next highest increases were Denmark and Norway, both with 0.1 and 0.2 years for females and males, respectively.

In contrast, the United States has seen a decrease in life expectancy, with losses of 1.7 and 2.2 years for females and males, respectively.

The researchers said Australia's quick response to the COVID-19 pandemic, including closing borders and implementing lockdowns, differentiated Australia's longevity outcome from that of the US.

"Australia was in a unique position to be able to close borders to the rest of the world. Now with the strong compliance on vaccinations, we are likely to be one of the safest places in the world," study co-author Professor Vladimir Canudas-Romo said.

"During the 1918 Spanish flu, attempts were made to close borders. Yet, once ports opened, the lack of a vaccination meant the virus spread with fatal effects. With modern-day vaccines, Australia has been able to escape this deadly fate."

The researchers said lockdowns led to longer lives because of a "sharp decline in the spread of other infectious diseases due to COVID-19 containment measures".

For example, there was a 20 per cent fall in deaths caused by pneumonia or influenza during Australia's lockdowns.

"Coronavirus was among the few causes of death that really increased from [2019 to 2020]... in the case of the US there was an extreme case of COVID strongly declining life expectancy," Prof Canudas-Romo said.

"[In Australia] even when mortality increased due to COVID, we still had so much decline in infectious diseases, accidents, heart attacks and strokes, that our life expectancy increased by three-quarters of a year."

Another key finding was a decline in social mobility triggered a large reduction in the number of road traffic accidents.

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Study co-author, Associate Professor Brian Houle, said the question remained whether this increased life expectancy would continue in a post-pandemic Australia.

"It's hard to make a long-term assessment for this unusual increase," he said.

"If working from home remains popular, with fewer people on the road commuting at peak times, that might result in reduced road accidents compared to before the COVID-19 pandemic."

The study was originally published in September 2021 by a research team from Oxford, with data from Australia not included. ANU researchers updated the study with data from Australia.