COVID-Related MIS in Kids: What Do We Know?

F. Perry Wilson, MD, MSCE


May 20, 2020

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This transcript has been edited for clarity.

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I'm Dr F. Perry Wilson from the Yale School of Medicine.

This week I want to talk about the children.

I am constantly thankful that COVID-19 seems to spare children. Can you imagine what the situation would be like if young kids were at significant risk? I have three young kids at home, and if there was a substantial risk to their lives, I'm not sure I could walk through those hospital doors.

But from the beginning, it's been clear that age is one of the most—if not the most—important risk factors for COVID-19 mortality, as these data from England show.


Data from Iceland give us more promising information. Using random screening of the population, 0 out of 848 children under the age of 10 tested positive by PCR for COVID-19, as compared with around 1% of those above age 10.

Putting these together, the early data seemed to say that kids were less likely to get the coronavirus, and if they did, were less likely to die.

As we consider how to reopen society, these data points suggest that opening schools may actually be a good first step. The concern of kids transmitting virus to more susceptible loved ones at home may be moot if they don't get it in the first place. And, of course, opening schools would relieve parents of childcare responsibility, allowing them to work.

But recently, new reports have called into question the nature of COVID-19 infections in kids.

On May 14, CDC issued a health advisory regarding multisystem inflammatory syndrome (MIS) in children, associated with COVID-19.

What is this thing? And how many kids are affected?

The syndrome is characterized by fever, hypotension, and organ dysfunction. Of note, respiratory symptoms do not appear to be universal.


Though MIS shares features of Kawasaki disease, the classic bilateral conjunctival injection, rash, and strawberry tongue aren't always present.

As with all things COVID-19, the first study we got on this topic was a case series. The Lancet article chronicled eight kids between the ages of 4 and 14 years, of whom six were of Afro-Caribbean descent. Three required mechanical ventilation. One died. All were either PCR- or antibody-positive for SARS-CoV-2. That's important—it seems like this syndrome can occur in the convalescent phase of the illness.

More data have come out of the New York State Department of Health. As of May 13, they are investigating 110 cases of MIS and three deaths.

The age distribution suggests that the highest risk is in the 5- to 14-year range, but be careful: These are very early data, and attribution bias may be at play here. Older kids with the syndrome may be diagnosed simply with COVID-19, which can lead to severe illness. If you don't think of MIS, you don't diagnose MIS.


The racial breakdown in New York City seems to be consistent with population averages, though there are a bunch of missing data here.


In New York, just 1% of those hospitalized are under the age of 20; that amounts to around 750 kids. With 110 cases of MIS, this is not super rare, at least among those kids who are sick enough to get to the hospital.

And that's the important take-home: The risk for this syndrome remains incredibly small.

We need more data, but here's my back-of-the-envelope calculation: If you started with 100,000 kids infected with COVID-19, we'd expect 5000 to be hospitalized. We'd expect 733 cases of MIS. Of those, we might see 20 deaths. That's 0.02%.

That is not zero. That means we need to figure out how to treat this syndrome as fast as possible. But it is also not high enough to keep me from walking through those hospital doors.

F. Perry Wilson, MD, MSCE, is an associate professor of medicine and director of Yale's Program of Applied Translational Research. His science communication work can be found in the Huffington Post, on NPR, and here on Medscape. He tweets @methodsmanmd and hosts a repository of his communication work at

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