Paeds ITU is very specialised and miles over my head. So take this with a pinch of salt.
It looks as though they’ve see some cases of very sick kids admitted to ITU with vasculitic (inflamed blood vessels) disease. Some (but not all) test covid positive for current disease. Some (but not all) have antibody levels which imply past exposure. So they’re worried this might be covid related.
There’s examples of people getting vasculitic rashes (a bit like chilblains) after recovering from covid in other countries. If it can cause a vasculitic rash, then it might cause damage to other organs in the same way.
https://www.ejpd.com/images/nuova-vasculite-covid-ENG.pdf
Some big caveats here:
-Numbers seem to be small.
-We don’t know if they have pre-existing illnesses
-The fact that some kids get very sick from covid is not news.
-There are vasculitic auto-immune diseases that make small numbers of kids very sick every year.