I agree children need to return to school when it's safe for them to do so.
But the reality is that many working age (and parent of school children age) clinically vulnerable adults will not have been vaccinated.
Where we are they are just starting in the CEV group. Hopefully they will have their first dose soon.
But as someone who is CV I can't see me getting my first vaccine for a while yet. Then it's another 3 weeks for that to kick in, and 12 weeks before dose 2.
This group accounts for a lot of teaching staff and parents. Once children go back full time, with no protective measures in place, the huge amount of mixing of numerous households starts again.