So few out of so many samples? I mean, useful to know since they had an effect, but it seems far from the most popular cause of MIS-C.

I wish I knew how to offer a simple idea to research teams:
Kids are more likely to put their hands in their mouths than adults. So what I think is that MIS-C COULD basically be a Covid-19 infection via the digestive system, rather than primarily the lungs (After all, a lot of their symptoms are in the abdomen, right?).

Covid affects endothelial cells, & the gut contains plenty of those!

Additionally, maybe Covid itself can pass through the gut-vascular barrier? If the particles are small enough & survive digestion (or even start being absorbed in the esophagus or stomach), then they might be taken up into the patient's various body systems?

The gut's endothelial cells are involved with what is allowed to pass from the intestine into the bloodstream. Couldn't the virus's infection of the digestive system's endothelial cells allow either the virus itself, or perhaps even other unwanted material such as gut bacteria, digestive enzymes, undigested food particles, etc. into the bloodstream & surrounding body systems?

Maybe they should also check such victims, as well as victims of Long Covid, for leaky gut, or other issues with the permeability of their guts' endothelial cells/gut-vascular barrier. Finding out whether they had any symptoms of such conditions before the infection (such as celiac disease, IBS, etc), & whether that may have affected their Covid outcomes, could be useful, & give us answers concerning both MIS-C & Long Covid.

If anyone knows if this has been/is being investigated, or where I could broadcast this idea, please let me know.