Long COVID, a complex condition with lingering symptoms like fatigue, chronic cough, and brain fog may be affecting far more people than once believed.

A recent AI-based study conducted by researchers at Mass General Brigham in Boston finds that nearly 23% or one in five U.S. adults report symptoms of long COVID. The new finding reveals a rate strikingly higher than the 7% prevalence suggested by previous studies.

"Questions about the true burden of long COVID -- questions that have thus far remained elusive -- now seem more within reach," said senior researcher Hossein Estiri, head of AI research at Mass General Brigham in a news release.The latest study utilized a specialized AI tool to navigate through medical records for symptoms of long COVID using a database of nearly 300,000 patients across 14 hospitals and 20 community health centers in the Mass General Brigham system. The novel technique called "precision phenotyping" sifts through individual records to identify symptoms and conditions linked to COVID-19, tracking them over time and distinguishing them from symptoms of other illnesses.

According to the U.S. Centers for Disease Control and Prevention (CDC), long COVID is a serious condition that occurs after SARS-CoV-2 infection leading to chronic conditions or disability. Although the exact number of people experiencing the condition is unknown, the CDC considers it a significant public health concern impacting millions of lives.