(NEXSTAR) – While it’s not clear exactly how many children suffer from long COVID, doctors who work with children are seeing some of them continue to struggle weeks or months after a coronavirus infection.

The warning signs may be harder to spot in children, who aren’t always able to properly name the symptoms plaguing them.

“The most common symptoms that we see for children who have long COVID are fatigue, difficulty concentrating and mood swings,” said Dr. Kimberly Giuliano, a pediatrician for Cleveland Clinic Children’s Hospital.

Those symptoms can be easy to miss. Parents may think their kid caught a cold at school, or is acting out if they experience mood swings. Brain fog and trouble concentrating may go unnoticed until grades at school start to slip.

Yale rheumatologist Dr. Ian Ferguson said he’s also seen young patients dealing with joint and bone pain after having COVID.

“They might say, ‘I just feel achy. I don’t feel right.’ An otherwise healthy child may say, ‘I don’t feel like I should get out of bed in the morning,'” Dr. Ferguson explained in a Yale Medicine article. “Or they say, ‘I used to be on the high school cross country team. And now I can barely make it down the street before I have to take a break.’”

Doctors encourage parents to be mindful of the common long COVID symptoms and monitor their children after an infection.

If the symptoms are impacting your child for longer than a week or two, Giuliano recommends getting them seen by a doctor.

“The pediatrician or family practice provider would spend some time trying to understand the timeline related to COVID and the onset of symptoms, how common these symptoms were for the child before the infection even started, and then put all those pieces together to determine what the best treatment option would be for them,” she said.

Long COVID can affect anyone who catches the virus, but is more likely to occur in cases resulting in severe illness or hospitalization. The best way to prevent serious illness is to stay up-to-date with vaccinations, the Centers for Disease Control and Prevention said.

Children between 6 months and 4 years old are eligible for a “primary series” of COVID-19 vaccines (either two doses of Moderna or three doses of Pfizer). Children 5 and older should get their primary series, the CDC says, as well as a booster if enough time has elapsed since the last shot.

You can check if you and your child are up-to-date with COVID shots on the CDC’s website.