Who'll Get Long COVID? Just a Look at a Patient Gives Clues
Sometimes just looking at a person can give clues to their likelihood of developing long COVID after a bout with the virus.
For example, obese people are five times more likely to suffer long COVID symptoms that persist at least three months after their infection clears, a major new U.S. study finds.
Another risk factor: Experiencing hair loss during COVID-19 illness, the same study found.
Headache and sore throat during infection also greatly increase a person's risk of long-haul symptoms, the researchers added.
However, the results also showed that other risk factors for COVID-19 infection do not necessarily mean a person will develop long COVID, noted senior researcher Eileen Crimmins, chair of gerontology for the University of Southern California and director of the USC/UCLA Center on Biodemography and Population Health.
"What's somewhat more interesting are the things that didn't matter," Crimmins said. "Gender didn't predict long COVID. Race/ethnicity didn't predict long COVID. And having conditions like hypertension [high blood pressure], heart disease, cancer, they didn't predict long COVID."
Overall, 23% of people infected with COVID-19 can be expected to develop long-haul symptoms, regardless of whether their infection was severe enough to require hospitalization, Crimmins and her colleagues reported. The study was published online recently in the journal Scientific Reports.
The World Health Organization defines long COVID as symptoms that last 12 weeks or longer after the initial infection has cleared, the researchers said.
"A significant number of people may have trouble working, taking care of their families, doing the things they need to do day-to-day because they've had the condition," Crimmins said. "So, it's not a nothing disease."
These numbers are based on the Understanding America Study COVID-19 National Panel, an ongoing regular survey of more than 8,400 U.S. adults.
Starting every two weeks in March 2020, panel members were asked to fill out a questionnaire detailing their health status and any symptoms they might be having.
During the following year, about 10% of total participants reported that they'd been diagnosed with or tested positive for COVID-19.
The researchers focused in on 308 people who had COVID-19 and had reported their health status and symptoms before, during, and at least three months after their initial diagnosis.
What factors influenced the odds of long COVID the most? Obesity increased a person's risk of long COVID by nearly five and a half times, the results showed. Other prominent risk factors included hair loss during infection, which increased sevenfold the risk of long COVID. Headache and sore throat each increased a person's risk by more than three times.
It's likely that obesity and hair loss are both tied to the amount of inflammation a person suffers during their COVID-19 infection, which can wreak havoc on their body's organs, explained Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases.
"Perhaps obesity allows that inflammation to persist for a longer period of time, therefore resulting in symptoms," Schaffner said. "Hair loss is kind of new to me, but that's obviously going to be some sort of symptom that relates somehow to inflammation."
Surprisingly, age, gender, race, education, smoking, and preexisting health conditions like diabetes or asthma didn't appear to influence the risk of long COVID.
The most common symptoms people developed during COVID that persisted months later included:
- Headache (22%)
- Runny or stuffy nose (19%)
- Abdominal discomfort (18%)
- Fatigue (17%)
- Diarrhea (13%)
The study did not find other symptoms that have been commonly reported by long COVID-19 patients, including brain fog and joint pain, Schaffner noted.
"So there are some things that reinforce what's in the literature and some other things that are a little different," Schaffner said.
Despite that, Schaffner praised the study as a "noteworthy addition to the literature" that should help the many long COVID centers that have opened up around the country to deal with this phenomenon.
"The main thing I take away from this is that long COVID is not unusual. In fact, it's rather common," Schaffner said. "It's persistent and it will require a great deal of medical attention going forward. A lot of medical resources will have to be devoted to this, and those resources will largely be outside the hospital, including supportive care, physical therapy and even some psychological support for these patients."
Crimmins added it could take years, and even decades, to fully understand the long-term effects of COVID-19.
Research into the 1918 influenza pandemic found that fetuses in utero when moms caught the flu had a 25% higher risk of heart disease by the time they were in their 70s, Crimmins noted.
"There are things that may happen in this population to their underlying health that may not be immediately obvious, but could have relatively significant long-term effects," Crimmins said of long COVID patients.
The U.S. Centers for Disease Control and Prevention has more about long COVID.
SOURCES: Eileen Crimmins, PhD, chair, gerontology, University of Southern California, and director, USC/UCLA Center on Biodemography and Population Health, Los Angeles; William Schaffner, MD, medical director, National Foundation for Infectious Diseases, Bethesda, Md.; Scientific Reports, July 8, 2022, online