An estimated 17.8 million Americans have suffered long COVID, researchers say.

Even months after a COVID-19 infection, some patients experience complications. About 18 million Americans have had long COVID, according to new research.

In a data brief published Friday by JAMA, researchers say about 7% of Americans have had long COVID as of early 2023. The findings reflect data collected by the Agency for Healthcare Research and Quality.

Women are also more likely to have developed long COVID. Researchers say 8.6% of women reported having long COVID, compared to 5.1% of men.

Long COVID symptoms can include fatigue, brain fog, persistent coughing, chest pain, and gastrointestinal symptoms, among others.

In the JAMA data brief, the federal researchers examined results from a survey of 17,418 adults 18 years or older. The survey found 8,275 respondents said they had COVID-19, and 1,202 adults reported that they had symptoms of long COVID.

For the survey, researchers defined long COVID as symptoms lasting three months or longer after an initial COVID-19 infection.

Midlife adults were more likely to say they had long COVID than younger adults (ages 18-34) and those over the age of 65, the researchers found. White and Hispanic patients were more likely to report symptoms of long COVID than Black and Asian Americans.

Individuals with chronic conditions such as chronic bronchitis, emphysema, asthma, and heart disease were more likely to say they had long COVID. But researchers found that Americans with lower incomes weren’t more likely to report symptoms of long COVID than those with middle incomes and high incomes, researchers said.

The findings support earlier federal research. In 2022, the Centers for Disease Control and Prevention published data estimating that 6.9% of Americans have had long COVID. But researchers who published the new data pointed to the significance of more women reporting symptoms.

The new data brief came in the same week that the National Academies of Sciences, Engineering, and Medicine published new research about the impact of long COVID.

The National Academies report found that those with long COVID can have difficulty at work or school for a long period of time. Some symptoms, including chronic fatigue or “brain fog,” can affect individuals for six months to as long as two years after infection, the report states.

Some can experience severe complications even if their initial COVID-19 infection was fairly mild, the National Academies report stated.

Paul Volberding, professor emeritus in the department of medicine at the University of California, San Francisco, and chair of the committee that wrote the National Academies report, said in a news release that treating long COVID is difficult.

“This disease, which has existed in humans for less than five years, can present differently from person to person and can either resolve within weeks or persist for months or years,” Volberding said in a statement.

Another study published in Nature Medicine in August 2023 found that the complications of long COVID can persist for up to two years.

Some researchers have called for a greater commitment to studies of long COVID. In an article published by Science in February 2024, Ziyad Al-Aly and Eric Topol wrote about the need for physicians to have a greater understanding of symptoms.

“Importantly, the care needs of people with Long Covid are unmet,” they wrote. “Patients are often met with skepticism and dismissal of their symptoms as psychosomatic. The attribution of symptoms to psychological causes has no scientific support; it perpetuates stigma and disenfranchises patients from accessing the care they need.”

Some lawmakers have criticized the federal government for not moving more aggressively to study long COVID to devise better treatments.

Independent U.S. Sen. Bernie Sanders has been among the loudest voices pushing for better treatment for patients of long COVID. At a hearing in January, Sanders said too many patients with long COVID have struggled to get their symptoms taken seriously.

“Far too many medical professionals have either dismissed or misdiagnosed their serious health problems,” Sanders said at the hearing. “This crisis is made even worse by the fact that long COVID patients often require multiple specialists to treat their complex symptoms.”