• Health
  • COVID-19

Almost 25% of COVID-19 Patients Develop Long-Lasting Symptoms, According to a New Report

4 minute read

A year and a half into the pandemic, the condition known as Long COVID continues to stump doctors. A significant number of patients develop long-term symptoms after catching COVID-19, but it hasn’t been clear why that happens, who is likely to get sick or even how many people continue to suffer.

A large new study may help form some answers to those questions. In line with prior estimates, it finds that almost a quarter of people infected with the virus develop at least one lingering health problem, and that most Long COVID symptoms are more commonly reported by women than men.

The report was released on June 15 by health care nonprofit FAIR Health and has not been published in a peer-reviewed journal. FAIR Health analyzed private health care claim records for nearly 2 million people diagnosed with COVID-19 in 2020. The people in the study ranged in age from babies to the elderly; some 53% were female and 47% were male.

Twenty-three percent of them reported one or more health issues at least 30 days after being diagnosed with COVID-19. The most common included pain, breathing trouble, high cholesterol, malaise and/or fatigue and high blood pressure. But the reported post-COVID symptoms were quite varied, running the gamut from depression and anxiety to skin conditions to heart issues and gastrointestinal distress.

Patients with serious cases of COVID-19 were most likely to report a post-COVID condition, but the study shows that people can develop Long COVID even after a mild initial case of COVID-19. Half of the people who were hospitalized for COVID-19, then discharged, developed at least one issue lasting 30 or more days, followed by 27.5% of people who were symptomatic but not hospitalized and 19% of people whose claims never reported an acute COVID-19 symptom. That finding refutes the idea that young, healthy people will be fine after a COVID-19 infection—even for those with symptom-free cases, there can be lasting consequences.

While patients of all ages and genders reported post-COVID conditions, their specific symptoms varied somewhat depending on demographic. For example, gastrointestinal issues were the third most common symptom among pediatric patients, but the 11th most common among patients ages 40 to 49. And high cholesterol was the second most common symptom among patients ages 50 to 59, but the 13th most common among kids.

Symptoms also varied by gender. Previous studies have suggested that Long COVID is more common among women than men, and the new research supports that conclusion. Fifty-eight percent of the people who developed post-COVID symptoms were female, and most of the symptoms analyzed appeared more frequently in women. But certain issues, like heart disease and kidney failure, affected men significantly more often.

Deaths among people in the study were fairly uncommon. Less than 0.5% of patients who were hospitalized for COVID-19 and then discharged died more than 30 days after their initial diagnosis; the number was even smaller among non-hospitalized and asymptomatic patients. Regardless of their initial case’s severity, men were more likely to die during the study period than women, consistent with general COVID-19 trends.

Patients with certain chronic conditions, including cancer, HIV and kidney disease, were excluded from the study, given their likelihood of having health issues unrelated to COVID-19 after diagnosis. But other preexisting conditions that didn’t disqualify an individual for inclusion, such as substance use, asthma, developmental disabilities and dementia, did seem to raise the risk of dying or developing a serious post-COVID condition. It’s also possible, the authors write, that certain post-COVID symptoms—like high blood pressure and cholesterol—were present but undetected in some patients before they got COVID-19, and were only picked up when they sought medical care after diagnosis.

There are still many unknowns about Long COVID, including—most notably—why it happens. Some experts believe remnants of the virus linger in some people’s systems, causing lasting health problems. Another theory is that COVID-19 nudges some people’s immune systems into overdrive, essentially causing the body to attack itself. More research is needed to say for sure, and to develop treatments for Long COVID.

The new report presents plenty of new questions. Why, for example, do symptoms vary so much by age and gender? But it also offers robust estimates about the prevalence of Long COVID and who is likely to experience it—findings that could offer a jumping off point for studies to come.

More Must-Reads from TIME

Write to Jamie Ducharme at jamie.ducharme@time.com