I obviously try and draw conclusions from how other countries experience this pandemic, so when I see France keeping schools open AND showing a dramatic decline in reported cases, I tentatively conclude schools are not a major transmission vector. They have shuttered bars, restaurants, barber shops, gyms, and the like, and you need permission to move around more than 1 km from your house. It's a pretty severe lockdown, other than schools, and it appears to be working, somewhat to my surprise.
The economic cost is obviously severe.