i don't know why you think a children's vaccine is impossible .. next week they'll likely open up the pfizer shot to 12 year olds and they're already doing studies on 5-11 year olds.
I expect by the fall we'll have public school vaccination requirements
I don't think a children's vaccine is impossible, I said it was very questionable at the moment. I think herd immunity is impossible for a variety of reasons but if a children's vaccine hits a stumbling block then that would definitely be a huge blow to the chances of herd immunity