I wrote this on another thread:
"However, the main issue, it seems to me, are the implications for the wider school community. Teachers live with and care for vulnerable and shielded elderly or vulnerable young relatives. Pupils live with vulnerable or shielded parents. Children travel to school on crowded buses, driven by further adults, and, in many areas, also populated by standard commuters or key workers, on their way to or from nursing homes, hospitals etc. Grandparents, often elderly, are key to before and after school childcare.
The key implication of re-opening schools is a MASSIVE reduction in social distancing across the community of adults linked to that school. Adults walking their children to the school where the children will mix freely are highly unlikely to remain 2m from every other adult on the same errand, or to believe that they can see a friend on the school run but not go round for a coffee (before then perhaps going on to their workplace).
Essentially, in one step, we go from small socially-distanced households to, essentially, the entire community linked to a single school becoming, as far as virus transmission is concerned, a single household, linked by a route the virus is entirely capable of travelling. As many people have children in more than 1 school, each school-linked community then becomes linked, to an even larger network.
It is that, not the simple fact of children being in school, that worries me. Yes, (quite a few) teachers and (a few) children will die when schools re-open, through direct in-school transmission. However, many in the school linked community will ALSO die, and it is the latter numbers that should concern us all."