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“It’s not the virus itself, it’s the inflammation that the virus causes,” Siegel told "America's Newsroom."
The condition has also been reported in recent weeks in pediatric coronavirus cases in New York and the United Kingdom.
At least three patients at Children’s Hospital Los Angeles displayed signs of the pediatric inflammatory multisystem syndrome, or PIMS, which doctors have said is similar to Kawasaki disease, or a condition that causes swelling in medium-sized arteries throughout the body.
Kawasaki disease, which primarily affects children and has less than 6,000 diagnosed cases in the U.S. each year, often leads to inflammation in the coronary arteries, according to the Mayo Clinic.
Siegel said that the ailment was seen in children ages five to 15 years old, cautioning parents to look for gastrointestinal symptoms for signs of a larger problem.
“That’s what we’ve been dealing with in COVID-19 all along. Not the virus, but the damage it does from inflammation,” Siegel said.
“Tragically, we’re seeing the involvement of the heart muscle. We’re seeing inflammation of the arteries of the heart. That’s the biggest concern here.”
Siegel said that, on the other hand, the good news is that when children are treated with “Gamma globulin” or “intravenous antibodies,” there is a “usually a rapid response.”
“That, plus aspirin and, sometimes, steroids, most of these kids get better. And, if they are on the ventilator, which is rare, they get off fairly rapidly. But, overall, this responds to treatment,” Siegel said.
Fox News' Madeline Farber contributed to this report.