Lingering breathing problems and complications in the weeks and months after suffering COVID-19 illnesses were most common in women and in patients who didn't need hospitalizations or suffer severe initial infections, a new Mayo Clinic study found.

The roundup report offered several surprises about the first 100 patients to receive care through Mayo's rehabilitation program for so-called "long haul" post-COVID symptoms. Only 25% of the patients had been hospitalized for COVID-19, according to the study by Dr. Greg Vanichkachorn and colleagues that was published in Mayo Clinic Proceedings.

"We are not seeing that hospitalization is a huge risk factor for this prolonged COVID state," said Vanichkachorn, medical director of Mayo's COVID-19 Activity Rehabilitation Program (CARP).

The study is among the first to not only address the mystery of who suffers post-COVID syndromes, but also the types of symptoms they endure. Eighty of the 100 patients reported fatigue while 59 reported breathing problems and 59 reported neurological symptoms ranging from headaches to dizziness. Forty-five reported cognitive impairments, such as fogginess in memories and thoughts.

While 91 patients had been working before COVID-19 illness, only 63 were back working and 29 had returned to full hours.The prevalence and nature of post-COVID symptoms has been poorly understood, though a few studies have offered estimates and the National Institutes of Health recently named the syndrome as post-acute sequelae of SARS-CoV-2 (PASC).

Mayo's rehab program started last year with an initial definition of the syndrome as someone experiencing symptoms four or more weeks after a positive test for SARS-CoV-2 infection. The average age of the patients in the study was 45, and the majority did not have underlying health problems before infections.

Vanichkachorn said the fatigue in patients was severe enough to link to COVID-19, rather than to related issues such as depression and anxiety caused by isolation during the pandemic or other issues.

"It's not like 'I'm always sort of tired,' " he said. "Its like, 'I take my dog for a walk or do some light gardening and then I take a four-hour nap or I have symptoms for the next two, three days.' Some people will tell me it's like all of their life energy is sucked out of them."

Basing the study on the first 100 people to seek post-COVID care at Mayo creates some limitations, including that certain demographics might be more likely to seek medical care for problems that others might try to endure on their own.

The patients in the study on average were evaluated 93 days after infections. Vanichkachorn said the findings are helpful in that they identify the common symptoms, which could motivate patients to seek screening for rehab care sooner.