Many patients with mild to moderate COVID-19 could become "long haulers," suffering symptoms months after they clear their non-life-threatening infection, new research shows.
About 33% of COVID-19 patients who were never sick enough to require hospitalization continue to complain months later of symptoms like fatigue, loss of smell or taste and "brain fog," University of Washington (UW) researchers found.
"We were surprised to have one-third of people with mild illness still experiencing symptoms," said lead researcher Jennifer Logue. She's a research scientist with the UW department of medicine's division of allergy and infectious diseases, in Seattle. "If you contract coronavirus, there's a good chance you could experience a lingering effect."
These results show why everyone should protect themselves against coronavirus infection, given that the 177 Seattle-area patients tracked in the study were relatively young and healthy, said Dr. Kristin Englund, an infectious disease specialist who leads the Cleveland Clinic's COVID long-hauler recovery clinic.
More than 90% of the patients (average age: 48) suffered only mild to moderate COVID-19 and didn't need hospitalization, the study authors said. Few had health problems that would put them at risk for serious COVID-19 infection (for example, only 13% had high blood pressure, 5% had diabetes and 4.5% were active smokers).
"It's not just our hospitalized patients we have to focus in on," Englund said. "There are a lot of patients out there who can still continue to have these persisting and really life-altering symptoms."
Nearly 28 millionCOVID-19 infections have been reported in the United States, which could mean millions of Americans suffering from symptoms that last months and possibly years, she said.
"If you take 30% of that who could have potential impacts on their quality of life in the next six to nine months, we're talking about huge numbers," Englund said.
The potential to suffer long-term symptoms from COVID-19 infection increased slightly with age, Logue's team found.
About 27% of patients between 18 and 39 years of age reported persistent symptoms, compared with 30% of those between 40 and 64, and 43% of those aged 65 and older, the findings showed.
According to Dr. David Hirschwerk, an infectious disease physician with Northwell Health in Manhasset, N.Y., "The likelihood of this occurring appeared to be age related, with older patients more likely to report ongoing health effects after the initial infection."
While the University of Washington study is small, the numbers reported from Seattle are similar to what medical centers are seeing elsewhere in the United States and around the world, said Dr. Thomas Gut, director of ambulatory care services at Staten Island University Hospital in New York City.
"It's remarkable how we have different data sets now from England, from Canada, from China, and from the U.S. now, and we're all kind of seeing a similar pattern that emerges," Gut said.
That pattern is confirming that the SARS-CoV-2 virus that causes COVID-19 is "a little nastier than a lot of the other viruses we've had to deal with," said Dr. Ravindra Ganesh, an internist at the Mayo Clinic in Rochester, Minn.
Such long-term symptoms are usually associated with viruses like Epstein-Barr, West Nile and chikungunya, all of which are much less infectious than the novel coronavirus, Ganesh and Gut said.
"It has a severity that's closer to those than to most common viral pathogens," Ganesh said.
Overall, nearly 33% of COVID-19 patients who suffered through their illness at home and 31% of hospitalized patients reported at least one symptom from the disease that persisted months later, the researchers found.
The most persistent symptoms among the Seattle patients were fatigue (14%) and loss of smell and taste (14%).
Brain fog or memory complaints were reported in about 2% of the patients, but this is becoming one of the most notorious long-hauler symptoms, Gut and Ganesh said.
"The brain fog's particularly debilitating to folks who do a lot of intellectual work and often work from home via computer," Ganesh said. "They just can't focus on the computer that long, and the bright lights bother them and give them headaches. They're just not as productive as they used to be, and it's very frustrating for them."
Nearly 31% of patients said they had a worse health-related quality of life now, compared to before getting COVID-19, the researchers reported.
It's not yet clear why COVID-19 causes these lasting effects.
Many viruses are capable of creating what's known as "post-viral syndrome," which experts describe as health problems that persist long after the infection has cleared the body. These are the result of inflammation or other damage that occurs as the immune system fights off an infection.
But there's evidence that at least some COVID-19 long-haul symptoms might be directly attributable to the coronavirus itself, Gut said.
"Because it has a direct effect on the nerves of our nose, we think that likely there is an effect on brain structure. We know that definitively there are changes in our lungs that occur from it," Gut said of COVID-19. "It has far-reaching implications we're just now beginning to understand since we're just starting to categorize the syndrome."
The findings were published online Feb. 19 in JAMA Network Open.
The Cleveland Clinic has more on coronavirus long haulers.
SOURCES: Jennifer Logue, BS, research scientist, division of allergy and infectious diseases, department of medicine, University of Washington, Seattle; Kristin Englund, MD, infectious disease specialist, Cleveland Clinic, Ohio; David Hirschwerk, MD, attending infectious disease doctor, Northwell Health, Manhasset, N.Y.; Thomas Gut, DO, associate chair, medicine, and director, ambulatory care services, Staten Island University Hospital, New York City; Ravindra Ganesh, MBBS, MD, internist, Mayo Clinic, Rochester, Minn.; JAMA Network Open, Feb. 19, 2021, online