Thoughtful https://abs.twimg.com/emoji/v2/... draggable="false" alt="🧵" title="Thread" aria-label="Emoji: Thread">on schools from a public health insider. Why high community transmission is key:
"As cases increase, contact tracing is going to go the way of the dodo again. This includes contact tracing for schools ... When that goes, I don& #39;t think schools can be open anymore." https://twitter.com/PHealthGnome/status/1381062047094411264">https://twitter.com/PHealthGn...

In other words, you can have a "relatively" safe protocol that works fine when case rates are low. But once a region hits high rates, the PH protocol begins to implode due to resource constraints. Contact tracing is not scalable, it& #39;s human.

I don& #39;t believe the Ontario agent-based modelling that supported school opening included this factor. That may help explain why "bottom-up" simulations have a disconnect with "top-down" statistical cross-country modelling. Given the known contact tracing issues, this seems impt.

This is why I have focused most of my school comments on community transmission risk levels. They are like floodwaters, once they reach a certain stage there are not enough sand bags.