About 10% of people infected with Omicron reported having long COVID, a lower percentage than estimated for people infected with earlier strains of the coronavirus, according to a study published in JAMA.
The research team looked at data from 8,646 adults infected with COVID-19 at different times of the pandemic and 1,118 who did not have COVID.
“Based on a subset of 2,231 patients in this analysis who had a first COVID-19 infection the National Institutes of Health said in a news release.
People who were unvaccinated or got COVID before Omicron were more likely to have long COVID and had more severe cases, the NIH said.
Previous studies have come up with higher figures than 10% for people who have long COVID.
For instance, in June 2022 the CDC said one in five Americans who had COVID reported having long COVID. And a University of Oxford study published in September 2021 found more than a third of patients had long COVID symptoms.
The scientists in the most recent study identified 12 symptoms that distinguished people who did and didn’t have COVID. The scientists developed a scoring system for the symptoms to set a threshold to identify people who had long COVID, the NIH said.
The symptoms were fatigue, brain fog, dizziness, stomach upset, heart palpitations, issues with sexual desire or capacity, loss of smell or taste, thirst, chronic coughing, chest pain, and abnormal movements. Another symptom was postexertional malaise, or worse symptoms after mental or physical exertion.
Scientists still have many questions about long COVID, such as how many people get it and why some people get it and others don’t.
The study was coordinated through the NIH’s RECOVER (Researching COVID to Enhance Recovery) initiative, which aims to find out how to define, detect, and treat long COVID.
“The researchers hope this study is the next step toward potential treatments for long COVID, which affects the health and wellbeing of millions of Americans,” the NIH said.
A version of this article first appeared on WebMD.com.