By Gary Evans, Medical Writer

Although the pandemic of SARS-CoV-2 (COVID-19) has been relatively benign in children compared to adults, there is growing concern about an emerging syndrome that causes severe, sometimes fatal outcomes in pediatric patients.

The Centers for Disease Control and Prevention has named this condition multisystem inflammatory syndrome in children (MIS-C). The CDC recently issued a case definition and urged reporting of any case. The CDC case definition for MIS-C is summarized as:

• An individual aged < 21 years presenting with fever, laboratory evidence of inflammation, and evidence of clinically severe illness requiring hospitalization, with multisystem (> 2) organ involvement (cardiac, renal, respiratory, hematologic, gastrointestinal, dermatologic, or neurological); AND
• No alternative plausible diagnoses; AND
• Positive for current or recent SARS-CoV-2 infection by RT-PCR, serology, or antigen test; or COVID-19 exposure within the 4 weeks prior to the onset of symptoms.

The CDC recommends that “healthcare providers report any patient who meets the case definition to local, state, and territorial health departments to enhance knowledge of risk factors, pathogenesis, clinical course, and treatment of this syndrome.”

We sought some insight from Samuel Dominguez, MD, PhD, an infectious disease physician at Colorado Children's Hospital in Aurora, who has been treating children with the syndrome, .

“Based on the epidemiology, these kids are appearing after about 4 weeks of the peak of COVID-19 cases overall in the areas where they are seeing this,” he says. “What we are seeing most likely is an immune reaction or some sort of post-infectious inflammatory response to the virus. The vast majority are presenting with a pretty severe gastrointestinal complaints, severe abdominal pain, some with vomiting and diarrhea.”

Some of children are in shock when they are brought in and must be admitted to an ICU for blood pressure support, Dominguez says.

“All of these kids have multiple days of high fever and evidence of pretty higher inflammation in the body,” Dominguez says. “Some of them are presenting very similar to Kawasaki disease, meaning conjunctivitis, rhinitis, and rash.” 

All of the children with the syndrome at Children’s Hospital have survived, but there have been deaths due to MIS-C reported in the United States and Europe, he says. The CDC call for case reports should provide some much-needed data on the syndrome. “We don’t actually know how rare this is,” Dominguez says. “I think there have been over a hundred cases reported in New York state. We don’t know the baseline of how many kids have been infected and how many people are in this population. So, there are multiple levels of trying to determine the incidence and prevalence. We think so far that is relatively rare, but I think we need more data to understand the exact rate.”

MIS-C is linked to coronavirus in the case definition by CDC, but it is not thought that the syndrome itself is transmissible since it is an inflammatory immune response.

“We are basing our infection control on whether they have a positive PCR test or evidence of active viral shedding at the time they are admitted to the hospital,” he says. “There is no evidence that someone who has MIS-C in the hospital can transfer that to another [patient] or their family, but they can definitely transmit SARS infection. And some patients who have SARS infection can go on to develop this more serious presentation due to their reaction to the virus. Who those kids are we don’t really know. At this this point in time we don’t know what the risk factors are.”

The implications for children returning to school are weighty, as some parents may see even a rare risk as too dangerous to expose to kids.

“That’s the million-dollar question,” Dominguez says. “I think the school decisions are best left to our public health authorities. I still think that this is a relatively rare event. The vast majority of kids who are getting infected with SARS-CoV-2 are doing very well compared to their adult counterparts.”