Very interesting paper distilling the (still quite patchy) evidence base on schools and COVID transmission. Nothing radically new, but further affirmation that while the picture is murky, the risks are non-trivial. A few notable observations:
Most countries that have reopened schools have done so with significant modifications: 
In Sweden, where elementary and middle schools remained open with little modification, there appears to be significant seroprevalence among kids, suggesting schools could be a factor (although other variables could also be affecting this).
Denmark has seen little impact of school reopening on transmission - but reopened with 1) significant modification to school protocols and 2) low overall transmission.
There is some evidence that school closures helped slow overall transmission. Countries with low transmission have been able to safely reopen schools, but Germany has seen increased transmission among students, and Israel has had re-close several after school-based outbreaks.
Overall takeaway (with admittedly thin evidence available) reaffirms that schools can be sources of transmission, and the safest way to reopen them is with low local transmission and meaningful adaptations to enhance safety. We're not doing well on either of those in the US.
If we want schools to safely reopen (I sure as hell do) we need federal and state govt to lay out a game plan for how we meet the twin aims of suppressing community transmission and helping schools meaningfully adapt. Not simply say "schools are important so just get them open."
