Andy Flosdorf never had a positive diagnosis for COVID-19, because tests were tightly rationed by the state when his symptoms started in late March 2020.

But the 51-year-old health care consultant in Minnetonka is still feeling the effects of COVID a year later — fatigue, brain fog, episodic chest pains and headaches. His so-called Long COVID symptoms were recently diagnosed as chronic fatigue syndrome, another poorly understood disorder.

"There's tired, there's fatigue, there's exhaustion. And then there's something past that, which is where I've been much of the year since," Flosdorf said.

On a bad day, he said, "The weight of your arms supported by a recliner becomes uncomfortable ... You're too tired for your eyes to be able to work the way they should be working."

Not everyone who has long-lasting multi-system effects months after COVID end up with chronic fatigue syndrome, also known as myalgic encephalomyelitis (ME/CFS).

But evidence from a handful of studies so far, using self-reported outcomes, shows high numbers of patients reporting lingering problems.

An international online survey, promoted in Long COVID support groups on social media, created a cohort of 3,762 patients who described 205 symptoms in 10 organs. More than 95% had symptoms longer than 90 days, and just over a quarter reported having a positive COVID test. The survey closed in May 2020.

Study results published in January, though not yet peer-reviewed, found 78% experienced fatigue, 72% had "post-exertional malaise," and 55% had cognitive dysfunction — the top three symptoms.

Patients say some symptoms come and go, like the wave of debilitating headaches Flosdorf had last September and October.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, cautioned Americans last year that scientists still don't understand the virus' long-term consequences.

"Even after you clear the virus, there are postviral symptoms," Fauci said. "It's extraordinary how many people have a postviral syndrome that's very strikingly similar to myalgic encephalomyelitis/chronic fatigue syndrome."

Yet Flosdorf is not alone in finding it hard to get doctors to pay attention to his problems. His symptoms are difficult to prove with objective tools like lab results, and he lacks a positive COVID test. The absence of a diagnosis allowed his employer's long-term disability insurer to deny benefits, even though his employer had been supportive.

Inconclusive results

It's not clear how many Minnesotans lost the chance to be diagnosed with COVID following the March 17, 2020 order limiting who could be tested. Others were tested early in the pandemic, only to be told their results were "inconclusive."

Lauren Kurth, 36, of Plymouth, had a nasal swab at a drive-through clinic just hours before the order limiting testing to hospital patients was imposed.

"My test took 20 days to come back," she said. "My nose was really dry at the time, and I told them that. I don't know if my specimen was frozen, if that affected it. But when I got my results … it came back inconclusive."

Kurth's family, friends and doctors pointed out she never had a positive result. Meanwhile she's had a battery of evolving symptoms, from exhaustion to sleep disturbances to fibromyalgia.

The former neonatal nurse said she has gone to the hospital emergency department more than 30 times for breathing problems. These days she gets oxygen through a nasal tube continuously and nebulizes medications six to eight times per day.

Yet even in the emergency room, Kurth said, "They have to mention, 'By the way, your COVID result was negative.' ... This is a year later, and they have to rub it in my face still?"

Flosdorf and Kurth said they tested negative for COVID antibodies once those tests became available. But not all COVID patients produce antibodies, and Flosdorf's doctor said the antibody tests last spring were "far from sophisticated" — they didn't quantify antibodies or distinguish between different types.

It remains to be seen whether a new lab-based test that measures changes in T cells following COVID infection will lead to more diagnoses for Long COVID patients.

Seattle's Adaptive Biotechnologies got FDA authorization last month to sell the first test that detects COVID by analyzing T cells in the blood more than 15 days after symptoms begin.

An uphill battle

There's no ready pool of doctors with the necessary expertise who can quarterback the complicated issues faced by the silent wave of Long COVID patients. Patients say it feels like they're on their own, that it's up to them to figure out which specialist to see next or when it's time to bolt on a doctor.

Dr. Greg Vanichkachorn, a doctor with the Mayo Clinic's post-COVID treatment program in Rochester, said patients need to advocate for themselves, particularly those lacking a formal diagnosis. Mayo's post-COVID program doesn't accept patients without a positive test result.

"Patients still face an uphill battle," he said. "They often get told that their condition is due to things like depression or anxiety, or they just need to toughen up. For patients who don't have that [positive COVID] test verification, things are even tougher."

In Minneapolis, M Health Fairview opened its Adult Post-COVID Clinic in December and accepts patients who got sick before tests were widely available.

"I think a majority of our patients actually didn't go to the hospital" for acute COVID, said Dr. Tanya Melnik, a physician with the M Health program. For those patients, she said, "The general expectation in the public is still 'Why are you complaining? You were not really sick?' I think that still is the perception in some physicians."

Chronically fatigued

"Long COVID" is a term coined and adopted by internet-connected patients — and then by many in the medical community — to describe a constellation of symptoms, from foggy thinking to fibromyalgia.

Long-term problems from COVID can include damage to organs like the lungs, heart and kidneys, and difficulties recovering from intensive care. But "Long COVID" often applies to the more mysterious lingering symptoms, like extreme fatigue and difficulty concentrating, which can appear even in patients who were never hospitalized with acute COVID.

Some cases, like Flosdorf's, start to overlap with those of chronic fatigue syndrome. His doctor, Dr. Ruby Tam with Northwest Family Physicians in Crystal, has diagnosed two cases of ME/CFS in post-COVID patients, including Flosdorf.

Dr. Jeffrey Siegelman, an emergency department physician with Emory University in Atlanta, said he understands firsthand the struggles with uncertainty attached to a Long COVID diagnosis.

In a column last year in the Journal of the American Medical Association, "Reflections of a COVID-19 Long Hauler," Siegelman wrote how comforting it was when his own physician validated his symptoms and his employer showed it understood the limitations of diagnostic testing.

"The reality is, whether I tested positive for COVID or not, I have these symptoms," Siegelman said Friday, in an e-mail. "In my mind, the focus must be on symptoms, rather than on error-prone testing."

Staff writer Jeremy Olson contributed to this report.