One of the nation’s top experts on Long COVID explains that it’s still a mystery why virus symptoms remain months and sometimes years after an infection. Dr. Leora Horwitz helps lead the National Institute of Health’s study of Long COVID. She’s the director of the Center for Healthcare Innovation and Delivery Science at NYU Langone Health, where they’re integrating the research activities of almost 200 clinical sites.

She says they have found evidence of the virus persisting as well as inflammation or irritation in the bodies of some patients, which may be contributing to the condition.

Hosts Mark Masselli and Margaret Flinter also ask Dr. Horwitz to explain the new working definition of Long COVID, which is helping the medical community move beyond any one individual symptom to describe it.