Tackling difficult walking tracks in the bush with a heavy pack was a big part of Greta Cunningham's life before long COVID transformed her days.
Like many Australians, the 44-year-old public servant contracted COVID for the first time early in 2022, and she was lucky to experience fairly mild symptoms when she fell ill.
But eight months on, it's taken Ms Cunningham dozens of specialist appointments, significantly reduced work hours and a lot of determination to achieve a 45-minute walk.
"I just never really recovered," she said.
"I started to get better and then the symptoms morphed into what I now know is long COVID.
"It was a pretty terrifying time as I collected more and more symptoms and didn't know what was going on."
Among those symptoms was cognitive dysfunction, often dubbed brain fog, extreme fatigue and the loss of taste and smell — which have since returned.
Those symptoms prevented Ms Cunningham from being able to work, and she had to use up all her sick leave and dip into savings to get by. She has only recently been able to return to work, slowly building her hours back up.
The resident of the inner-Melbourne suburb of Collingwood said after realising how limited official support was, she had "cobbled" together her own rehab team which included a physio and an occupational therapist.
"I couldn't do anything for many, many months, or very little," she said.
She said her team and online programs designed for people with long COVID helped her understand how slow and gradual her recovery needed to be
"At the moment I can walk now for 45 minutes, which is pretty good, I'm happy with that," Ms Cunningham said.
"But that's a long way off being able to carry a 20-kilo pack and walk for nine days in the mountains."
Australia missing data on long COVID numbers
Many thousands of stories like Ms Cunningham's are playing out across the country as people who made it through their initial COVID infections grapple with ongoing symptoms of varying severity.
An inquiry into long COVID is underway in the federal parliament, and Australian health professionals are learning more and more about the condition from their overseas counterparts.
But as a fresh wave prompted by the arrival of new Omicron sub-variants sweeps the country and waiting lists for dedicated long COVID clinics blow out, some say the issue flying "under the radar" needs urgent attention.
Fresh modelling from the University of Tasmania and Deakin estimates that up to 500,000 people could be experiencing long COVID by the beginning of December, with more than a fifth of those cases suffering "significant impacts".
The World Health Organization defines long COVID as an illness that usually occurs within three months of a COVID-19 infection, with symptoms and effects that last for at least two months.
University of Tasmania researcher Martin Hensher said the modelling of long COVID figures was based on COVID case numbers between the start of 2021 up to September 4 this year.
He described the 500,000 figure as the "upper estimate".
"Our lowest model suggests 160,000 people as the minimum," Professor Hensher said.
He said his team "had to do modelling, because there isn't very good actual data" and big surveillance programs should be set up to track long COVID numbers across the country.
"Australia's now well behind, almost all of our peer countries have been doing big surveys of long COVID for a while," Professor Hensher said.
"We're completely in the dark."
Call for 'proactive' response to condition
Neuroscientist Lucette Cysique said she was concerned about the long-term trajectory of the many thousands of Australians suffering the effects of the condition.
Dr Cysique leads a University of New South Wales team that has been studying the ongoing effects of COVID on the brain since early 2020.
The team found that two years on, up to a quarter of the participants had some ongoing cognitive difficulties.
"I think why it's maybe going under the radar is because those long-term cognitive difficulties ... they're not severe deficits," she said.
"The term brain fog is actually quite appropriate ... it stops you concentrating on something difficult.
"So people can probably go about their life at a minimum, but they can't engage in something cognitively demanding, and that's why it has such an impact on people's capacity to work."
Dr Cysique said in Australia, funding for research into COVID-19 and its effects was scarce, and clinics set up to deal with long COVID patients were "completely overwhelmed", with long waiting lists.
Although dedicated long COVID clinics have been set up across the country, many patients face a months-long wait to be seen, and some have even begun to close as funding dries up.
Melbourne's Austin Hospital, which has treated almost 300 people, will close at the end of the year when its funding wraps up.
"The community can continue to access direct support via their GP or via the GP respiratory clinics," an Austin Health spokesperson said.
Dr Cysique said countries like the US and the UK had invested far more resources into research and support.
"We need to have a local response," Dr Cysique.
"The research will inform to what extent people are suffering, what type of people are suffering and where we need to concentrate the resources in terms of health care."
She said for patients waiting for help, urgent action was required.
"For some people now it's a matter of urgency, there needs to be something done now — not in six months, 12 months — because for some people the disruption to their lives is actually quite severe," Dr Cysique.
The neuroscientist said in her view the situation would worsen the longer it was left unaddressed.
"Rather than being resolved, the situation is slowly collapsing onto itself," she said.
"It's having it's own life."
"In terms of chronic conditions like this, it's never good to react, it's better to be proactive.
"But it means much more resources, much more forward thinking, and I think we're missing that at the moment."
She also said more prevention was needed and masks should be strongly recommended, if not mandated, in some settings to help reduce the number of infections in the current wave.
Withdrawing long COVID resources a 'big mistake'
University of Queensland's Paul Griffin, an infectious diseases physician, said the main challenge posed by long COVID was there was "too many unknowns" relating to prevention, diagnosis and treatment.
"The answer to nearly every question at the moment is still 'I don't know'," he said.
"Like the rest of our response to the pandemic, we need to try and gather more information, collect some really good data and address some of those unknowns so that we can improve the outcomes.
"I guess the one thing we do know is it's very significant and it's only going to increase."
Dr Griffin said the two main schools of thought about the cause of long COVID were theories that it is an immune response to the initial infection, and that it is direct activity of the virus.
"I think that's much less likely given we're talking about a long duration and it would be very rare for a virus like this to persist for that long," he said.
"So I think it probably is some sort of immunological overcorrection or overreaction to the virus."
Dr Griffin said it was unclear how multiple COVID infections contributed to risk of long COVID, and whether avoiding it after one infection lowered people's risk of developing the condition after a subsequent infection.
"We often think that people will get some protection from past infection, but there's nothing to say that you can't get long COVID on repeated infections, and some people would say your risk of some of those longer-term complications would be increased from successive infections," he said.
"I don't think either argument has been proven conclusively yet, but the main thing is that you shouldn't get complacent after being infected once and just assume that repeated infections are not going to cause you problems."
He said the removal or resources dedicated to managing both acute and long COVID was disappointing.
"There's so few of those clinics around the country at the moment, the demand was very high at the outset. To remove funding instead of greatly expanding it is a big mistake.
Dr Griffin said the best thing was for people to wear masks and stay up-to-date with vaccinations.
"If you don't get COVID, you can't get long COVID," he said.
'On a good trajectory' to recovery
For most people, even if they experience long COVID, the evidence suggests they will fully recover.
"We think that the majority of people will make a full recovery in time," Dr Griffin said.
"But the issue is it can be a long period of time and some people can be quite severely impacted during that time to the point where they struggle to maintain their activities of daily living or work or study."
Ms Cunningham said while recovering, she felt forgotten once the public focus started to shift away from COVID.
"It does feel like we're forgotten. It's a silent pandemic, or a hidden pandemic," she said.
"Nobody wants to talk about it, it's too uncomfortable."
"The only things we seem interested in measuring or understanding are people who died, and even that's on the back page now.
"Or the number of cases, maybe.
"But what about people in the middle who are left disabled or damaged?"
Despite the challenges she is still facing, Ms Cunningham said she feels optimistic about the weeks and months ahead.
"I'm on a really good trajectory now, I'm really recovering," she said.
"I hope I recover fully."
