July 21, 2022 -- People who reported sore throats, headaches, and hair loss soon after testing positive for COVID-19 may be more likely to have lingering symptoms months later, according to a recent study published in Scientific Reports.

Researchers have been trying to determine who faces a higher risk for developing long COVID, with symptoms that can last for weeks, months, or years after the initial infection. So far, the condition has been reported in both children and adults, healthy people, and those with preexisting conditions, and a range of patients with mild to severe COVID-19.

“These people are not able to do necessarily all the activities they would want to do, not able to fully work and take care of their families,” Eileen Crimmins, PhD, the senior study author and a demographer at the University of Southern California’s Leonard Davis School of Gerontology, told the Los Angeles Times.

“That’s an aspect of this disease that needs to be recognized because it’s not really as benign as some people think,” she said. “Even people who have relatively few symptoms to start with can end up with long COVID.”

Crimmins and colleagues analyzed data from the Understanding Coronavirus in America survey, which followed nearly 8,000 people bi-weekly from March 2020 to March 2021. They focused on 308 non-hospitalized COVID-19 patients who were interviewed 1 month before their infection, around the time of infection, and 12 weeks after infection.

Among those, about 23% of the survey participants were still experiencing symptoms that lasted for more than 12 weeks, which the researchers considered as having long COVID. The most common persistent symptoms were headache (22%), runny or stuffy nose (19%), abdominal discomfort (18%), fatigue (17%), and diarrhea (13%).

Long COVID was nearly seven times more likely among COVID-19 patients who experienced hair loss and about three times more likely among those who reported headaches and sore throats.

“Our assumption is that hair loss reflects extreme stress, potentially a reaction to a higher fever or medications,” Crimmins told the newspaper. “So it’s probably some indication of how severe the illness was.”

Long-term symptoms were also more than five times as common among people with obesity. However, the researchers said there was a lack of evidence that long COVID risk was related to age, gender, race and ethnicity, smoking status, or other chronic conditions such as diabetes or asthma. Previous studies have indicated that these factors could play a role in long COVID risks.

Since the study covered the first year of the pandemic, the data doesn’t include information about vaccines or major coronavirus variants such as Delta and Omicron. The symptom list also didn’t include the most debilitating ones that long COVID patients have described to doctors, such as brain fog, cognitive issues, and memory loss.

“We need a universal case definition before we can really understand the prevalence of long COVID. Right now, the definition varies wildly across studies, leading to a big range in prevalence estimates,” Jana Hirschtick, PhD, MPH, an epidemiologist at the University of Michigan’s School of Public Health, told the newspaper.

“After all this time, we still don’t have a clear picture of who is at greatest risk,” she said.

Show Sources

Scientific Reports: “Long COVID and symptom trajectory in a representative sample of Americans in the first year of the pandemic.”

Los Angeles Times: “USC researchers identify symptoms associated with increased risk for long COVID.”

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