The Variant that is killing the most children so far is out of Northern Brazil: I reported this a couple of months ago

At that time it was killing Yanomami Children of that tribe in Northern Brazil. At that time it had already killed 9 children there. 

However, by now likely there are even worse variants killing children in South America and India and now spreading around the world too. So, it's important to consider children worldwide regarding vaccines at this point too to keep them alive and well ongoing.