As I mentioned, I'm no longer keeping track; last I checked was in early May, and at the time the disease was not yet called MIS-C. My sources were google searches.

My credentials are in math and engineering, not medicine.

However, due to unfortunate personal and family issues, I've read tens of medical papers and found statistical errors in many, maybe most of them -- I have literally saved at least one person from a life of misery based on finding these errors (and got apologies from department heads in two of the world's 10 top hospitals)

I don't know if Kawasaki is considered a post viral problem - either officially or unofficially. I did not look at the disease mechanics, only at disease prevalence. Symptoms are close enough (and the disease having a clinical description, NO direct biomarkers) that mis-identification is a real problem and known issue with these kinds of rare diseases.

The disease I'm very familiar with, unfortunately, shares a lot with kawasaki - including in how often it is misidentified as some benign condition. It was considered, though never proved, a post-viral autoimmune disease for years -- and likely still is by many doctors -- even though the "post viral" aspect is overwhelmingly a secondary aspect (something has to trigger the immune system, it's sometimes a viral episode, sometimes a vaccine, sometimes spontaneously)

> They clearly considered Kawasaki as a comparison too.

Kawasaki is a clinically identified disease, as is MIS-C. There's no specific biomarker to say "this is one and not the other". Right now, everything COVID-19 is shiny and well funded, whereas older things are not.

> Is Kawasaki syndrome already considered a post-viral problem?

As of a few months ago, at least half of the MIS-C cases were, to the best of everyone's knowledge, unrelated to COVID-19. see e.g. https://www.thelancet.com/journals/lancet/article/PIIS0140-6... which summarizes the state-of-the-art of knowledge as of May (The lancet is written in a confusing way, but https://www.dicardiology.com/article/kawasaki-inflammatory-d... is more clear - the relation to COVID-19 is not clear cut)

Here's a similar point: Last I checked, a few weeks ago, death from the flu all over the world has gone to zero, though in european countries and most of the US since June, death is as expected (statistically indistinguishable from expected rate of death). Flu death has gone to zero; COVID death exists when non did before. What's more likely - that FLU disappeared overnight but COVID has exactly the same rate of death? Or that both COVID and flu take a toll on the weaker and immune suppresed population (whose size didn't really change), but that the deaths are all attributed to COVID even though part (perhaps a third or half) as attributable to the flu? See e.g. https://www.nytimes.com/interactive/2020/04/21/world/coronav... - despite the April time, it IS up-to-date as of 22-aug, and you can definitely see the COVID death toll in europe on Mar-Jun -- but not anymore.

> Are you saying these children had Kawasaki already, or that Covid19 infection causes Kawasaki?

It is my belief based on knowledge of diseases OTHER than Kawasaki was that the predisposition was there, just waiting for the trigger, and would likely have erupted sooner or later, because of a flu, another virus, or some vaccine -- autoimmune diseases are often triggered when the immune system goes into high gear but them something goes wrong and they start attacking the body instead.

I am not saying they had Kawasaki already -- they obviously did not, because -- by definition -- Kawasaki is a set of symptoms (they did not have). However, I'm hypothesizing that everything was ready for Kawasaki, and something just caused it to erupt. It's also possible that COVID-19 was that trigger, and that it causes a slightly different disease progression than "standard" Kawasaki, although there's no such thing either- these diseases are never textbook cases of "These 10 symptoms == kawasaki", but rather "If we have more than 4 out of this list of 14 then we will label it Kawasaki unless we have a better explanation".

I am being vague with specific details of the diseases I am familiar with, so as not to out myself - it's rare enough that everyone involved knows everyone else on a first name basis. (Though as far as anyone's concerned, I might as well be a dog on the internet)