These interventions aren't harm-free, though, even putting aside the obvious effect on children's education. Nurses, doctors and other key workers have children and shutting down all the schools is going to be very disruptive to them. A surprising number of countries rely on schools to make sure some children are actually fed. There's also the problem of policing what those children do when they're out of school. And on a darker note, schools are a very important early warning system for domestic violence and abuse against kids, and there are some frankly very worrying claims that murders of kids have spiked dramatically in at least some parts of the US. It's likely that there are children who are dead now that wouldn't be if countries hadn't taken the "prudent option" of imposing a probably-ineffective intervention, quite possibly a substantial number.