ROCHESTER, Minn. — A Mayo Clinic study of patients with so-called long COVID suggests the syndrome is debilitating, afflicts a younger population than expected, and appears unrelated to underlying conditions or pre-existing mood disorders.

The study, of the first 100 patients enrolled in a Mayo Clinic program for outpatients with long COVID, was published this week in the journal Mayo Clinic Proceedings. It joins numerous attempts at describing the mysterious syndrome, but is one of only a few such papers to look at its effects on persons who were, for the most part, never even hospitalized for COVID-19.

With 75% of those studied having been treated for COVID-19 only as outpatients, the report suggests predicting those who will get the condition remains difficult.

There is only a limited understanding of long COVID, which the CDC describes as "ongoing health problems people can experience more than four weeks after first being infected with the virus that causes COVID-19." It is believed to afflict anywhere from 10-30% of those who get the illness.

"What we found is that there is not a pre-existing condition that leads people to have prolonged COVID states," said Dr. Greg Vanichkachorn, coauthor of the paper and clinician in the division of Preventive, Occupational and Aerospace medicine. "I don't think what these people are suffering from is just a manifestation of depression or anxiety, although that can occur."

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Dr. Greg Vanichkachorn recently coauthored a paper on the first 100 patients in the Mayo Clinic Long COVID rehabilitation program. Photo courtesy Mayo Clinic
Dr. Greg Vanichkachorn recently coauthored a paper on the first 100 patients in the Mayo Clinic Long COVID rehabilitation program. Photo courtesy Mayo Clinic

The first 100 enrollees in a Mayo Clinic COVID-19 Activity Rehabilitation Program (CARP) were monitored mostly through telemedicine to help them return to the functioning they had prior to contracting COVID-19. The authors watched the patients during the last seven months of 2020. The patients were 68% women, an average of 45 years old, and on average arrived at the program three months after first contracting the illness.

While the average participant was like much of the American adult population — just surpassing the threshold for obesity with an average BMI of 30 — most of the CARP patients studied had no pre-existing conditions prior to contracting the illness. Only a third had faced mood or anxiety disorders prior to contracting long COVID, and just over a fifth had asthma or other respiratory problems

Despite this relatively healthy cohort, long COVID took a toll on them.

The most common symptom reported was fatigue, afflicting 80% of those studied. This was followed by respiratory problems, including difficulty breathing in nearly 60% of those studied, and neurologic complaints described as "brain fog" in nearly 60% of those studied, as well.

Patients also reported problems with sleep, cognition and mood.

"I have heard from patients often accused that their symptoms were due to pre-existing depression or anxiety that came to the surface because of this COVID-19 stress," Vanichkachorn said. "But in our population, we did not find that the majority of patients had any form of depression or anxiety."

Vanichkachorn said only about 34% had the mood disorders in their past, and even fewer, only 4%, had pre-existing chronic fatigue problems.

Functional life deficits of long COVID were major

"We really wanted to get an idea of how these patients were doing at a functional level," Vanichkachorn said. The study determined a third of those with long COVID were so debilitated with fatigue, respiratory and other symptoms, that they had trouble with the very basic activities of life.

"These are activities which if you couldn't do them reliably, you might be in a nursing home," Vanichkachorn said, and included activities such as taking a shower, putting on clothes, doing hair and makeup and eating. An even greater proportion — 84% — had trouble with household chores, driving and hobbies.

While 91% of those studied had been working prior to their illness, 63 of the 100 patients were back to some work, while 31% had yet to return to work at all.

The neurological complaints observed in the patients included concentration, difficulties with speech and multi-tasking.

"If someone's hauling around an O2 canister or wheezing, it's really easy for others to understand these people have been sick and are hoping to get better," Vanichkachorn said. "But when someone's back at work and not able to do things they normally do, that's when employers are thinking 'what's wrong with you?'"

Mayo recently announced it is collaborating with the Minnesota Department of Employment and Economic Development for RETAIN, a program to get 3,200 workers from across the state suffering injury or illness back to their jobs over the next four years. The U.S. Department of Labor recently awarded that program $19.5 million.

Vanichkachorn believes there will be a coming long-hauler toll on society.

"There's been roughly 29 million cases of COVID-19 in the United States," he said. "A conservative estimate of 10% come down with long term COVID-19, so that's 2.9 million people. Our study found that 30% had not been back to work in any form."

"So 30% of 2.9 million is roughly 900,000 individuals who have not been able to get back to normal function at work after several months. These are teachers, doctors, nurses and firefighters. This means the post-COVID problem is not just a health care problem, but also a problem for our society and our country."