Over 75 Percent of Long Covid Patients Were Not Hospitalized for Initial Illness, Study Finds

The organization also plans to analyze how many patients in the study were vaccinated and when, Ms. Gelburd said. More than three-quarters of the patients in the study were infected in 2021, most of those in the last half of the year. On average, patients were still experiencing long Covid symptoms that qualified for the diagnosis four and a half months after their infection.

The findings suggest a potentially staggering impact of long Covid on people in the prime of their lives, and on society at large. Nearly 35 percent of the patients were between the ages of 36 to 50, while nearly one-third were ages 51 to 64, and 17 percent were ages 23 to 35. Children were also diagnosed with post-Covid conditions: Nearly 4 percent of the patients were 12 or younger, while nearly 7 percent were between ages 13 and 22.

Six percent of the patients were 65 and older, a proportion that most likely reflects the fact that patients covered by the regular Medicare program weren’t included in the study. They were much more likely than the younger groups with long Covid to have had pre-existing chronic medical conditions.

The insurance data analyzed did not include information about the race or ethnicity of patients, researchers said.

The analysis, which Ms. Gelburd said was evaluated by an independent academic reviewer but not formally peer-reviewed, also calculated a risk score for the patients, a way of estimating how likely people are to use health care resources. Comparing all the insurance claims the patients had up until 90 days before they contracted Covid with their claims 30 days or more after they were infected, the study found that average risk scores went up for patients in every age group.

Ms. Gelburd and other experts said the scores suggested that the repercussions of long Covid are not simply confined to increased medical spending. They signal “how many people are leaving their jobs, how many are being given disability status, how much absenteeism is there in school,” Ms. Gelburd said. “It’s like a pebble thrown into the lake, and these ripples circling that pebble are concentric circles of impact.”

Because the study captured only a privately insured population, Dr. Ssentongo said, it almost certainly understates the scope and burden of long Covid, especially since low-income communities have been disproportionately affected by the virus and often have less access to health care. “I think it may even be worse if we added in the Medicaid population and all these other people that would have been missed” in the study’s data, he said.