BOSTON — When it comes to MultiSystem Inflammatory Syndrome in Children [MIS-C], doctors can tell you when it happens and what it generally looks like. As for why it happens, that is still a puzzle.
“It mimics this illness we call Kawasaki Disease,” said Dr. Michael Koster, director of the Division of Pediatric Infectious Diseases at Hasbro Children’s Hospital in Providence, R.I. “And so, because of that, a lot of researchers are looking to see whether there are genetic factors with this or particular risk factors that may make someone have more severe MIS-C.”
The one known risk factor at this point: infection with or exposure to COVID-19.
“About four to six weeks after COVID’s either been in a family or household is when we typically see this in kids,” Dr. Koster said.
What doctors typically see is a febrile child who may also be suffering from severe gastrointestinal symptoms that could include pain, vomiting and diarrhea. Some kids will have a rash and a reddening of the eyes as well as fatigue.
But some cases of MIS-C can involve major organ systems.
“Cardiologists have been very involved with some cases of MIS-C because of the risk of cardiac complications, which happens in about 2/3 of patients,” said Dr. Audrey Dionne, a pediatric cardiologist at Boston Children’s Hospital.
The most common cardiac complication, Dionne said: a general weakening of heart function. That can lead to cardiogenic shock, a condition in which the heart cannot pump sufficient oxygenated blood to vital organs in the body.
There can be other issues, she said.
“The blood vessels that supply the heart, they can get enlarged or dilated. And we’ve also seen children present with arrhythmias; either their heart rates are too fast or too slow,” Dr. Dionne said.
The Centers for Disease Control and Prevention is keeping track of cases of MIS-C in the United States, and it’s clear most children survive the syndrome. At present, the CDC reports 2,060 cases of MIS-C from 48 states, Puerto Rico and the District of Columbia. Thirty of those patients died.
Massachusetts is one of 18 states with the highest case counts of MIS-C, with 51+ reported. In recent weeks, Hasbro and Boston Children’s saw, predictably, children with MIS-C from COVID-19 exposures at the end of 2020.
“The number of MIS-C cases really follows the trend of COVID cases four to six weeks later,” Dr. Dionne said. “So we saw a lot of cases in May at the beginning. Things kind of quieted down, then we had another surge in January likely reflecting the peak of COVID cases around the holidays.”
“I would say we’re sort of on the downslope of seeing the number of cases presenting each day,” Dr. Koster said. “I would say probably we’ve seen somewhere around 20 cases at Rhode Island Hospital, with a good number of them that we’ve been able to rule out that have had other illnesses or potentially mild cases of this syndrome.”
What’s concerning for pediatric hospitals nationwide is the possibility that, despite declining COVID-19 infection numbers, the virus may not be done with us yet and, in particular, may have found ways to conquer an elusive demographic: children.
“Under the age of 5, under the age of 8, for some reason kids just don’t seem to get [COVID-19] the way they do, for instance, influenza, where they’re often the ones spreading it everywhere,” Dr. Koster said. “We still don’t know the exact reason why. The main hypothesis is those receptors you’ve probably heard about, which are the ACE receptors in the nose. For some reason, the kids may not have as many of them, or the function of them may not attach as well to the virus.”
Enter the virus variants.
“Once the virus undergoes mutation, it may attach stronger to some of those,” Dr. Koster said. “Even if kids have fewer of them, it’s possible they may get more infections.”
And that will logically translate to more cases of MIS-C, Dr. Koster said.
“I think most experts out there from [Chief White House Medical Advisor Anthony] Fauci to [University of Minnesota epidemiologist Michael] Osterholm to other people we follow a lot in the news suggest that the mutant strains – there’s a lot of them here now – we’re looking at possibly another surge in about four weeks, and we really need to prepare for that,” Dr. Koster said.
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