Even a mild case of COVID-19 can come with some pretty miserable symptoms, including debilitating headaches, extreme fatigue and body aches that make it feel impossible to get comfortable.

To make matters worse, it’s becoming more and more apparent that a subset of people who’ve “recovered” from COVID-19 will go on to experience symptoms that linger well beyond testing negative for the virus. These individuals are sometimes referred to as “COVID long-haulers,” and experts are searching for answers about this condition that’s now being termed post-COVID syndrome.

“We’re seeing continued evidence that a fair number of people who have had COVID-19 continue to feel the effects of this illness for weeks to months after recovering from the worst of their symptoms or complications,” says Dr. Sandeep Lahoti, gastroenterologist at Houston Methodist who is leading the COVID-19 Recovery Clinic. “We still don’t understand how long these symptoms can truly persist, but we do know that many of these people would benefit from specialized care and, in some cases, regular follow up.”