At least five hospitals in the U.S. have started pediatric long-haul clinics to help kids with lingering COVID-19 illness as the National Institutes of Health and the Centers for Disease Control and Prevention mount a massive, nationwide study of long-haul COVID that includes children.

While many children do not experience severe COVID-19 illness, the coronavirus can have a lasting and serious impact on their health. 

At the request of CBS News, one hospital in Omaha documented how it is trying to help a girl who is struggling with the lingering effects of the virus. 

Twelve-year-old Piper Sibert has been battling extreme fatigue for the last two months. She has been going to the Children’s Hospital and Medical Center in Omaha to build back her endurance. 

These days when she gets to run, it’s in rehab, to the encouragement of medical staff cheering her on. 

“It is scary because you don’t know if you will do something that could make you stop breathing,” Piper told CBS News’ David Begnaud. “It’s just kind of a squeezing. It almost feels like someone’s sitting on your chest.”

Piper’s mom Sarah said her husband tested positive for the virus in November, but no one else in the family got sick. Then one day in February, Piper was sent home from school. 

“Just went from a really active kid to very lethargic, wore out,” Sarah Sibert said. “We took an antibody test and that proved that Piper had indeed had COVID at some point but we don’t know exactly when that was.”

Dr. Jean Ballweg, who runs the Clinic for Pediatric Long Haulers, said these young patients are not showing the signs she expected. The clinic treats about 10 patients like Piper each Friday. 

“I think most of us would have expected that really symptomatic kids with acute COVID were the ones that were going to have symptoms for months, and that is just not what we’re seeing,” she said.

And patients like Piper have a long road to recovery.

“I’m frustrated that there’s not a cure for it and something that can make it go away,” Piper said. “I don’t get to do the things that I really like and enjoy to do.”

Long-haul COVID is also different from another pediatric condition associated with the virus, Multisystem inflammatory syndrome of children. The latter illness is associated with high fever, rash and stomach pain.

Nearly one in five COVID-19 cases within the last week of March were in kids under 18.

Health experts say the coronavirus variant that was first discovered in England is driving a spike in coronavirus cases in several states.

The director of the National Institutes of Health said it is likely 70% more infectious and significantly more deadly, even for young people. 

However, Brown University School of Public Health Dean Dr. Ashish Jha offered some optimism in an appearance on “CBS This Morning” Monday.

“These vaccines are really remarkable,” Jha said. “They seem to hold up very well against all the variants, against the U.K. variant that’s spreading widely, it’s terrific. Even against some of the more tricky variants, it seems to be largely holding up.”

Dr. Ashish Jha on COVID-19 surges