3. Many countries have this number so large that it sounds like "all of them" (How many children there are in China compared to the 106 mln quoted, and of what age?) and one would expect more granularity at this point. Did they actually test 105 mln Chinese children? Does Serbia even have 900k children in the whole country?

While true, the figure above is almost 9% of the deaths. If true, that’s well beyond “a few extra deaths”. (I am somewhat skeptical that it’s a correct figure, or at a minimum if correct, that it carries 5 significant digits of precision.)