Whether he did or didn't, isn't the point. There are millions of children with "underlying health conditions" as yet undiagnosed - because they are children. I am quite certain this child would not have died recently without the CoVid.
At any rate, kids have underlying conditions that are not yet diagnosed and they would be the ones at risk, if it's ever shown that it's mostly kids with underlying conditions.
I don't think we can test every single child for every known illness. We cannot know before the child is ill or dies that they were the one who was going to get the Kawasaki style syndrome. Genetic studies of the suffering children will surely be done when doctors turn to longer term research projects, but in the midst of this pandemic, we're getting epidemiological information that alerts doctors for early signs (and the underlying conditions that do exist don't show any sort of underlying pattern so far).
But to answer your question, in the data available, most of the children with the Kawasaki-style symptoms did not exhibit any known condition, which is why the doctors are reporting and writing about it - in 20 nations now. Since it's rare, the data are in no way conclusive. The 9 newborns who died in China exhibited entirely different symptoms, AFAIK. There also seem to be some outlying cases that are not Kawasaki-style but almost entire involve what are essential heart attacks in children (again, it's the epithelial cell attack that CV makes that seems to be the mechanisms
Usually, the term "underlying health condition" means one that is medically diagnosed before an event, not something that is noticed only after death (which can include "pre-existing" conditions). At any rate, the vast majority of children who are at risk due to strange genes or undiagnosed medical conditions cannot be reasonably found and identified.
Fortunately, as @A Night Watchman pointed out, it's very few children. But the situation is concerning, since these kids are getting this syndrome a month or more after CV diagnosis (or without knowing that they'd had asymptomatic CV). Will it be the only syndrome of its type? Is it related to CV's attack on epithelial cells? (It would seem so). Will adults also be experiencing future attacks on their veins and arteries?
We don't know. And until we know, many parents are going to be very concerned. We know that many places shut their schools early, so CoVid has not yet had a chance to run rampant through a child-population.
Since the few cases of underlying conditions don't form a pattern, parents can't know in advance if their child is vulnerable. The mental stress of this kind of concern can be overwhelming and I think future mental health issues can be sure to follow in the wake of this pandemic.
Nice to see you are present and accounted for. Hope all is well with you.
