It’s been more than three years since Long COVID was first recognized as a condition, and despite billions of dollars and countless hours spent researching its causes and potential treatments, science has made little progress.

There could be a very good reason for that, argue public health experts Steven Phillips and Michelle Williams in an essay for TIME. It’s possible Long COVID isn’t a form of COVID-19 at all, but is actually encephalomyelitis/chronic fatigue syndrome (ME/CFS), a condition more commonly referred to simply as “chronic fatigue syndrome.” As Phillips and Williams note, certain viruses, like Epstein-Barr, are known to trigger chronic fatigue syndrome; the hypothesis they suggest is that SARS-CoV-2 can do the same.

If the scientific community embraces the theory, it could lead to a new paradigm in how the world thinks about Long COVID, halting research into the cause of the condition, and instead focusing on areas of study with more direct benefit to patients, like prevention, early detection, and symptom management. Perhaps more importantly, it would give the estimated 65 million Long COVID patients around the globe a more clear understanding of what's going on in their bodies.