Recently, a study published in the Lancet journal EClinicalMedicine garnered attention for listing more than 200 Long COVID-19 symptoms across 10 organ systems.
Though it supported only limited conclusions, the online survey of more than 3,700 self-reported COVID long-haulers in 56 countries gave voice to many who feel unheard and called for better screening and a broader clinical definition of Long COVID.
But David Engelthaler, director of TGen's infectious disease arm in Flagstaff, said its conclusions are hampered by ill-defined data.
"That's why we're seeing people having dozens of symptoms reported and seeing a lot that seem like they'd be outliers, that they haven't been really reported," he said.
Neuropsychologist Jim Jackson runs an ICU recovery clinic at Vanderbilt University in Nashville, where he also works with COVID long-haulers. Although he hesitated to criticize patient accounts, he agreed the study raises questions.
"When I think of people reporting that many symptoms, one thing I wonder about immediately is whether they're all distinct," he said.
A better designed study might have clarified whether any of the symptoms were redundant, overlapping or clustered together into syndromes.
Two key flaws further weaken the study: Three-quarters of respondents had not received a positive COVID-19 test, and researchers did not include a control group for comparison.
"We're not really comparing apples to apples. We don't know really in those respondents who truly was infected, who truly would fit into a category of long-haul COVID and what symptoms are truly associated with that long haul," said Engelthaler.
Turning Noise Into Signal
The patient-directed study's true significance might lie in its illustration of frustration: that Long COVID remains so poorly understood and disruptive that the authors felt the need to write it.
As for the data, they might defy easy comparison, but so do the various cognitive tests used by experts worldwide to evaluate long-haulers.
And even outlier symptoms could help experts better define Long COVID.
"That might be a good starting place; to say, 'Look, this is the panoply of possible symptoms that we can look at," said Engelthaler.
Michelle Villegas-Gold, associate director of health research at ASU Knowledge Enterprise, agreed.
"I think the large presentation of symptoms makes it extremely challenging, but we are seeing a certain cluster of symptoms that are presenting as the most common over and over across these studies, which is, I think, promising to start to understand this a little bit better," she said.
Hope for defining those symptoms and tying them to causes is growing. But research-over-time takes time. The National Institutes of Health recently extended funding for longitudinal studies, including one at University of Arizona.
Research is also increasingly hampered by a kind of burnout widely known as "COVID fatigue."
"The problem that we're finding with the hospital systems is that the people who are currently hospitalized for COVID are presenting as COVID fatigued, and they're not as eager to participate in research as some of the people that were presenting during previous waves," said Villegas-Gold, who says she talks regularly with the leaders of Arizona COVID-19 Long Haulers.
Meanwhile, experts have developed a fuller picture of the syndrome.
Revising The Picture
"Initially we were thinking — and this is possibly still true — that here's a brand new virus; it's not adapted to the human system, and so it's going to have a lot of what we would call 'off-target effects,'" said Engelthaler.
Jackson too has shifted his initial impressions.
"A year ago, I would have thought – and many of my colleagues, I think, would have thought – that there probably was a relationship between severity of COVID and severity of outcomes," he said.
But severity and outcomes don't always correlate in Long COVID or other post-viral syndromes.
Neal Woodbury, vice president for research at ASU Knowledge Enterprise, has seen similar patterns in his studies of Lyme disease, a tick-borne illness that causes symptoms not unlike Long COVID.
"It also has these long-term effects in a subpopulation of people, and it's a similar sort of thing. It's really quite dependent on the person," he said.
These experts aren't blaming the victims. They're saying syndromes like Long COVID might affect people differently due to biological differences.
"We are not clones. We are all different. We all have slightly different genetics. We have lots of different histories. We have different environmental conditions, different behaviors. All of that might lead into how we respond to any type of an infection, including COVID," said Engelthaler.
Those factors can complicate attempts to link symptoms to causes, especially if the patient suffers from an undiagnosed condition.
"The patient has a problem, and the medical community needs to help solve that problem. But it's difficult sometimes to tell what the cause of the problem is," said Woodbury.
The Force Of Frustration
That stark reality, combined with the powerlessness many feel in the face of byzantine medical codes and dismissive physicians, provokes frustration – and provides the impetus behind a movement called "patient-centered outcomes research."
"There's a lot of merit to the idea that I'm going to learn from you about what's bothering you, rather than tell you what I know is bothering you, even though you might not agree," said Jackson.
Long COVID's prevalence also brings unmatched attention to post-viral syndromes — and a unique opportunity to study them in a vast population.
"Certainly not an experiment we ever wanted to run, but we will try and gather the data, and I'm sure that data will be very helpful," said Woodbury.
Meanwhile, new questions arise: Do vaccines, breakthrough infections or variants affect Long COVID odds or outcomes? What does recovery look like, and how can medical systems and social safety nets help patients get there?
Barring those answers, and amid rampant COVID fatigue, COVID long-haulers bear an additional burden: keeping the issue alive in the public mind.