Uncertainty Surrounds Definition of Long COVID
Many people wonder if they have long COVID, but getting a clear answer depends on whom you ask. A recent study reveals that the medical community still doesn’t have a solid definition for this condition, even with numerous studies and millions of individuals affected globally.
Researchers reported their findings in JAMA Network Open, highlighting the inconsistency in how long COVID is defined. This lack of a clear definition can result in significant differences in the number of people diagnosed, making it challenging to provide proper care and treatment.
Lead researcher Lauren Wisk, an assistant professor at UCLA’s David Geffen School of Medicine, emphasized the need for a standardized definition. Various institutions, including the National Academies of Sciences, Engineering, and Medicine, have proposed their own versions of long COVID, but none of these definitions have gained wide acceptance due to their various shortcomings.
For example, the National Academies’ definition, introduced in 2024, is very broad and does not require proof that a person previously had COVID-19.
In their study, researchers examined five definitions of long COVID drawn from earlier studies involving over 4,500 COVID patients from the U.S., U.K., Netherlands, Sweden, and Puerto Rico. The definitions varied in terms of how long symptoms needed to last—ranging from four weeks to six months—and the number of possible symptoms, from nine up to 44.
Interestingly, the proportion of patients identified with long COVID varied widely, from 15% to 42%, depending on which definition was applied. This inconsistency can result in medical professionals overlooking genuine cases of long COVID or misdiagnosing others who don’t actually have it.
Senior researcher Dr. Joann Elmore noted that without a common definition, there’s a risk of mislabeling patients and misguiding their care, which is a significant concern for those affected.
Wisk also pointed out that these discrepancies hinder the medical field’s understanding of long COVID. She stated, “If every study uses a different definition for identifying who has it, it becomes much more difficult to draw meaningful comparisons across studies.”
She suggested that, in the absence of an objective measure like a blood test, researchers and doctors will need to choose the most appropriate definition for their specific inquiries and clearly communicate the limitations of their chosen methods.
For more information about long COVID, the U.S. Centers for Disease Control and Prevention offers valuable resources.
