More than one million Australians who contracted long COVID at the height of the pandemic cost the national economy almost $10 billion in lost productivity.
Academics from the Australian National University (ANU), University of NSW (UNSW) and Melbourne University have found around 100 million labour hours were lost in 2022 due to adults with the condition being unable to work or cutting hours.
Up to 1.3 million Australians were estimated to be living with long COVID at the time, the research found.
"We estimate this equates to economy-wide losses, on average, of about $9.6 billion in 2022, or one-quarter of Australia's real gross domestic product growth that year," ANU professor Quentin Grafton, one of the study's authors, said on Monday.
"Our research likely underestimates the economic impact of long COVID because it does not account for losses such as healthy employees who can't work because they're caring for others with long COVID."
Most workers affected by the condition were aged from 30 to 49.
Valentina Costantino, from UNSW's Kirby Institute, said the study showed MPs needed to place more emphasis on combating long COVID.
There were likely up to 873,000 Australians still living with the condition more than four years after COVID-19 first hit the nation, Dr Costantino said.
"A predominant focus of COVID-19 health policy is prevention of hospitalisation and death from acute COVID-19, with less attention given to long COVID," she said.
Another of the study's authors, Raina MacIntyre, said strategies to reduce COVID-19 and therefore long COVID should focus their attention on indoor air quality and improved ventilation.
"Financial assistance for long COVID patients, at least for those unable to work because of their symptoms, such as access to a disability pension, would reduce their economic burden," Professor MacIntyre, from UNSW, said.
Long COVID refers to long-term symptoms such as fatigue, breathlessness and joint pain that some people experience after they have had COVID-19.
The federal government in June announced $14.5 million in grants as part of a $50 million spend to generate better evidence on strategies to manage long COVID in the community.