More than two dozen lab tests have been unable to diagnose long COVID, according to new research which suggests there may be no reliable way to diagnose the condition.
Researchers from the US National Institute of Health compared questionnaires, and clinical lab results from participants in the study to investigate whether COVID-19 led to persistent laboratory abnormalities and whether symptoms were present.
The study published in the peer-reviewed Annals of Internal Medicine included more than 10,000 adult patients exploring COVID-19 and long COVID. It found none of the 25 routine lab results were clinically useful to diagnose someone suffering from long COVID.
So what is long COVID?
The Australian Institute of Health and Welfare has defined long COVID as cases where people experience symptoms about 12 weeks after the initial infection.
A joint study released in March by ANU and the Western Australia Department of Health found 90 per cent of participants with long COVID were suffering multiple symptoms.
Those symptoms included tiredness, fatigue, "brain fog", sleep problems, coughing, and changes in their menstrual cycle.
"Among respondents with long COVID who had worked or studied prior to their infection, 15.2 per cent had reduced their number of hours, and 2.7 per cent had not returned to work at all," the report said.
What does it mean that there is no single test to diagnose long COVID?
James Trauer, head of epidemiological modelling at Monash University's School of Public Health and Preventative Medicine, said it was better to think of long COVID as an umbrella term rather than a single condition.
He said the range of symptoms from shortness of breath, loss of smell, brain fog or fatigue were very different neurological, respiratory and cardiac symptoms.
"Some of them have more of a psychological overlay than others ... We need to consider it as multiple conditions. We need to start breaking it down into lots of different conditions," he said.
Dr Trauer said the way forward was to recognise the similarities between long COVID and other post-viral syndromes after contracting glandular fever or Lyme disease.
"Grouping [long COVID] in with them, and having a serious research effort into understanding what different immune responses lead to what different set of symptoms and how we can manage each of them differently," he said.
"If there's one silver lining from our experience with COVID-19, I would hope that people begin to pay a bit more attention to some of these other conditions.
"Patients have been complaining about [them] for a very long time, and they're also not associated with clear laboratory abnormality."
Does this mean there isn't a way to diagnose long COVID?
Burnet Institute senior research fellow Dr Michelle Scoullar specialises in long COVID at Clinic Nineteen.
She said there might not be a biomarker to diagnose long COVID but there were other ways to diagnose patients suffering from the disease.
"What we do have is a diagnostic criteria, a clinical criteria that we can access and use to make sure that people don't miss out on the diagnosis of long COVID," Dr Scoullar said.
"It's really important that we don't let this lack of a diagnostic marker get in the way of diagnosing people with long COVID, because we can do it now."
Dr Scoullar highlighted last year's parliamentary inquiry into long COVID, which recommended better data collection for COVID-19 and guidelines for treatment.
"So I guess following on from those is implementing them and supporting those things. Part of that is making sure that clinicians are aware of long COVID, aware of how to diagnose it, and then the next steps of what to do," Dr Scoullar said.
But some experts have called the federal government's response to the inquiry a missed opportunity.
In it's response to the inquiry, the government noted a recommendation to fund multidisciplinary long COVID clinics in major hospitals but said it was up to state and territory governments to decide how they spent existing funding.
Some experts say strengthening primary care will help long COVID patients
Dr Anita Muñoz, who is the chair of RACGP in Victoria, said in order to combat the lack of a simple reliable test for long COVID, there needed to be more resources directed to general practice.
"What needs to occur is a really thorough history, a thorough examination and the use of other tests and investigations to rule out the condition that can mimic long COVID," she said.
"So all of that takes time. It takes multiple appointments, and it does require the patients often to undergo a series of tests."
She said good clinical medicine was the only way to make a diagnosis of long COVID, and that could not be rushed.
"And unfortunately, the funding streams don't remunerate or reward clinicians for spending good quality time with their patients," she said.
Dr Jenny Huang, a GP in a long COVID clinic in Geelong south-west of Melbourne, said she often used the analogy of the response to floods and fires when speaking about the approach to long COVID.
"We can't ignore what is happening in terms of the fire or the flooding that's downstream and the people being caught in all of that. We can't just leave them to fend for themselves," she said.
Dr Huang believed she was only seeing the "tip of the iceberg" when it came to the impact of long COVID.
"I know that a lot of patients, they're coming to us four hours away, because they can't find the help from their own clinicians, whether that be GP or secondary care, they don't have that time to spend," she said.
"So the issue, unfortunately, is about again, supporting those on the ground that can help the patients, but [clinicians] also need those resources to help them."
