As the COVID-19 pandemic continues to wreak havoc worldwide, medical experts have been taking a more active approach to better understanding long COVID. But to this day, there is still not enough research on how the condition affects children.

Because the gravity of long COVID in kids remains unknown, there is still no official guidance on how to diagnose the condition and deal with the situation. A few studies did suggest that between 2% and 10% of children who had tested positive for COVID-19 would go on to develop the post-COVID syndrome.

Unfortunately, the lack of guidelines makes it hard for parents to determine if their child has the condition. Even healthcare workers and pediatricians are having a difficult time diagnosing it because the symptoms tend to vary from case to case.

Based on data collected by the American Academy of Pediatrics, almost 13 million children in the U.S. have tested positive for COVID-19 since the pandemic started. There is no concrete basis on how many of them developed or would develop long COVID.

“I personally believe that this is a very much an undiagnosed issue,” Dr. Sara Kristen Sexson Tejtel told CNN this week. She is among those helping lead the long COVID pediatric clinic at Texas Children’s Hospital in Houston.

In adults, about 30% of COVID-19 infections lead to the post-COVID syndrome. But even for them, it is challenging to diagnose the condition because there are no specific tests for long COVID.

UT Southwestern Medical Center in Dallas Division of Pediatric Infectious Disease chief Dr. Jeffrey Kahn and other experts shared the common symptoms they observed among their young patients.

Children with long COVID are said to present a wide range of symptoms, including fatigue, brain fog, headache, palpitations, chest pain, dizziness, and stomach problems. There are also cases of altered sense of taste and smell even after their initial bout with the virus.

Kahn also revealed that in some cases, children experienced heart failure after battling an asymptomatic COVID-19 infection. The problem typically showed up four weeks after infection, which was “really startling,” according to him.