One of the things that worries me about this (beyond the obvious education and mental health repercussions) is that we know obesity is one of the key factors in how well/badly people deal with covid after age.
And all of our children (who aren't in school) are now doing considerably less exercise than they were a year ago. ALL of the secondary age children I know have put on weight and/or lost muscle tone over the last year. They have gone from almost constantly moving to pretty much living the sedentary life of your average office worker.
There are no sports clubs, swimming, dance etc. No walks to/from school or the bus stop. No walking to meet friends and mooch around town.
My yr8 used to swim regularly, dance, PE 2/3 times a week, all day moving around the school etc etc. Now she does essentially nothing. She's allowed out for a walk/run once a day - except she has lessons during daylight hours so I have to practically force her to come out and walk a daily Mile with me. I'm under no illusions that if she were 15/16/17 the chances I could make her do that if she didn't want to are pretty slim. She's lost most of her muscle tone from exercise - no more abs for me to be jealous of - and put on weight. She's lucky that she was very slim before so she's still not overweight but it still can't be great for her health.
Some of my friends kids have put on a LOT of weight. Not because they're lazy but because they've nothing to do to burn off energy!
My little two are still at nursery/school (2 KW) and one of the biggest complaint I'm hearing from their friends parents who are wfm/homeschooling is that their sleep has gone to shit - everyone knows how full of energy little kids are, they've nowhere to put it. So they're not tired. So they are sleeping less.
All of these things are not something that children can just bounce back from - they will have longer term affects.
It's a crazy mixed up world when we're facing a virus that generally affects larger and unhealthy people worse and countering it by essentially forcing our young people to stop the majority of things they can do to enhance their physical health... what happens if we get a variant that does affect children and young people? We've set large numbers of them up to get it worse, haven't we?