As more kids are diagnosed with COVID-19, will MIS-C cases rise?

"Our greatest challenge is that we don't have any way of predicting how bad MIS-C is going to be," one infectious disease pediatrician told TODAY.

In the wake of a 40% increase in the number of kids with COVID-19 in late July, experts speculate that there could be an increase of cases of MIS-C in coming weeks. TODAY Illustration / Getty Images
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While much is still unknown about kids and the coronavirus, at this stage we do know that cases of COVID-19 in children are rising. And this may lead to more cases of multisystem inflammatory syndrome in children, or MIS-C, the mysterious and at times deadly illness in a small portion of kids infected with the coronavirus.

First reported in April and May, the rare condition can cause inflammation of body parts, including organs, according to the Centers for Disease Control and Prevention. In some kids, it can lead to organ failure and other life-threatening symptoms. Common signs of MIS-C include fever, abdominal pain, vomiting, diarrhea, neck pain, rash, bloodshot eyes or feeling extra tired.

MIS-C is still incredibly rare, experts stress. But with some schools reopening in person, likely increasing kids' exposure to the coronavirus, unanswered questions about MIS-C are more urgent than ever. Here's what we know about MIS-C now and how parents can protect their kids.

Are cases of MIS-C rising, too?

In the last two weeks of July, the nation saw about a 40% increase in COVID-19 cases in kids, according the American Academy of Pediatrics and Children’s Hospital Association. But it's unclear at this point whether this has led to a corresponding rise in MIS-C — and there are a few reasons why, Dr. Ermias Belay, an epidemiologist and the CDC's MIS-C expert, told TODAY.

First, the syndrome usually emerges two to four weeks after a child is infected with the coronavirus, so recent surges in the South and Southwest may just now be leading to new MIS-C cases. Second, the process of reporting new MIS-C data is lengthy and can delay access to this information.

As of July 29, 570 cases of MIS-C had been reported to the CDC. Belay said majority were in the Northeast, especially New York and New Jersey, which hit their peaks early in the pandemic.

"With the surge of (COVID-19) cases in the South and the Southwest, we anticipate cases (of MIS-C) to pick up," he said. "We haven't seen what we saw in the Northeast in other regions yet, but ... we anticipate that will change going forward."

Belay added that he's heard "anecdotally" that hospitals and physicians in the South have seen "an increased number of cases, but those cases have not been reported to (the CDC) yet."

The latest MIS-C data from individual states may support Belay's suspicion. Florida, which, in mid-July, broke the U.S. record for the most new coronavirus cases in one day, had reported 31 MIS-C cases as of Aug. 10, according to the state's department of health. In late May, there were only a few cases of MIS-C reported in the state.

In Louisiana, which was hit especially hard in March, there have been 44 cases reported as of Aug. 10 and four deaths. "Louisiana is seeing an increasing number of cases of MIS-C among young people," the department of health noted in a recent press release.

South Carolina, which experienced a surge of coronavirus cases in early July, had its first case of MIS-C on July 12, and at least six more have been reported since. Arizona and Texas had each reported between one and 10 cases to the CDC as of Aug. 6.

"Our greatest challenge is that we don't have any way of predicting how bad MIS-C is going to be," Dr. John Christenson, medical director of infection prevention for Riley Children's Health in Indianapolis, told TODAY. Riley treated 12 kids with MIS-C between May and early July, which mirrors Indiana's peak, Christenson said.

What do we know about MIS-C?

The syndrome occurs primarily in kids who were infected with the coronavirus, regardless of whether they showed COVID-19 symptoms at the time, Belay said, adding that there's no definitive medical test for whether a patient has MIS-C.

The age of documented MIS-C patients ranges from two weeks to 20 years old, with an average age of 8, according to CDC data. It seems more common in Latino and Black kids, as well as boys. About 64% of patients were admitted to an intensive care unit, and 10 of the 570 patients reported to the CDC died. In most patients, the cardiovascular and gastrointestinal systems were affected.

Dr. Keith Meyer, medical director at Nicklaus Children's Hospital in Miami, told TODAY that his facility, which has a dedicated MIS-C unit, has seen "a steady stream" of "one to two patients" a week since the pandemic began. He noted that older children tend to develop more severe cases of MIS-C, but it's not known why.

Meyer stressed that most children recover from the illness and that he's observed three types of MIS-C patients: mild cases that do not require medical care, which he believes are common; moderate cases where the child is admitted to the hospital and recovers within a few days; and cases with "severe systemic illness," as he described.

He added that in part, because of the mild cases, it's not known exactly how common MIS-C is.

While MIS-C often draws comparisons to Kawasaki disease, which also causes inflammation throughout the body mostly in children 5 or younger, it's a "distinct" illness, Dr. Leron Finger, chief quality officer at LCMC Health in New Orleans, told TODAY. "Most of what we know is that it’s real."

It's still unclear why some children develop MIS-C after a COVID-19 infection and others don't, and the driving factor behind the severe cases is also unknown, Belay said.

Per the CDC, there's no official recommendation for how to treat MIS-C. But intravenous immunoglobulin (IVIG), a type of antibody therapy and steroids have been used frequently.

What can parents do?

Belay said that the best strategy to protect children is to limit their exposure to the coronavirus by following standard protocols, such as mask-wearing, social distancing and regular hand hygiene. He also said that it's "very critical" for parents to know the signs of MIS-C.

For example, Christenson said he tells parents to look for fevers that they can't explain, skin rashes, red eyes and gastrointestinal symptoms, like abdominal pain.

Meyer added that even though parents might be scared of seeking medical care due to the coronavirus epidemic, they shouldn't delay calling their health care provider if their child shows any signs of MIS-C. That's "message one," he said.

The rates of the coronavirus in the local community can also help assess a child's MIS-C risk from attending school in person, according to Belay. The more COVID-19, the greater the risk.

That said, it's important for parents not to "panic," Dr. Gary Duhon, a critical care pediatrician at LCMC health told TODAY. "It's rare and most children do well with it," he added.