As the number of young people with COVID-19 in the state grows, Tennessee children's hospitals are starting to see pediatric patients with a mysterious illness believed to be connected to the coronavirus, known as multi-inflammatory syndrome in children.

The rare syndrome can cause inflammation in different parts of a child's body, including the heart, lungs, kidneys, brain, skin, eyes or gastrointestinal organs.

As of Sept. 3, the U.S. Centers for Disease Control and Prevention website reported 792 confirmed cases of multi-inflammatory syndrome in children (MIS-C) and 16 deaths in 42 states. Most of those cases were in children between the ages of 1 and 14, with an average age of 8 years old. The disease also has disproportionately hit Black and Hispanic children, with 70% of cases affecting these demographic groups, according to the CDC.

So far, Tennessee and Alabama have seen fewer than 10 cases of MIS-C, whereas Georgia has had between 10 and 20 cases, according to the CDC.

"This [syndrome] does happen, and it is being seen widely across the country in children as a 'post-infectious' complication of COVID," Children's Hospital at Erlanger CEO Dr. Charles Woods said by email. "It is relatively rare, and most children who develop this appear to recover fully, but we don't know the long-term outcomes for sure yet."

Children's Hospital at Erlanger, which serves the region around Chattanooga, has treated at least one child for the illness. A second possible case is pending confirmation, Woods said. Both of Erlanger's patients seem to be recovering well, he said.

Meanwhile, the Monroe Carell Jr. Children's Hospital at Vanderbilt has treated five patients with the syndrome since mid-July, according to a news release issued Tuesday.

Although MIS-C is rare, Vanderbilt childhood infectious diseases experts are advising parents to watch for symptoms, especially in children who have been infected with COVID-19, since they believe the two are related.

MIS-C can be serious and life-threatening, but if caught early can be successfully treated, said Dr. Ritu Banerjee, associate professor of pediatrics and pediatric infectious diseases at Vanderbilt.

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Staff photo by C.B. Schmelter / Dr. Charles Woods, CEO of Children's Hospital at Erlanger.

"The estimates are that around 90% of children who have MIS-C have evidence of COVID-19 or have had COVID in the recent past," Banerjee said in a news release. "There appears to be a strong relationship between COVID-19 and MIS-C, but what we don't understand is why, though we think it is an inflammatory response. We can't predict which children will get MIS-C and why some children develop these symptoms."

MIS-C symptoms are believed to develop two to four weeks after COVID-19 infection, according to Vanderbilt's news release. Parents should contact their child's doctor if children develop a fever, abdominal pain, vomiting, diarrhea, neck pain, rash, bloodshot eyes, swelling of hands and feet, feeling extra tired or experiencing changes inside the mouth, such as a red tongue.

More severe symptoms requiring emergency care include trouble breathing, pain or pressure in the chest that doesn't go away, new confusion or difficulty waking or staying awake.

Banerjee stressed that MIS-C is "extremely uncommon," and early data shows that only two in 100,000 people under age 21 will develop the inflammatory syndrome.

"Most children will be just fine after a COVID-19 infection, and when we do diagnose MIS-C, it is treatable," Banerjee said. "The best way to prevent MIS-C is to prevent COVID-19 infection in the first place — so that means practicing social distancing, masking and good hand-washing."

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