This study is important, and could possibly shed some additional light on why some studies haven't found #COVID19 spread in #Schools at higher levels.
Could the flaw be in our contact tracing methods and subsequently under testing? Let's explore. https://www.cdc.gov/mmwr/volumes/70/wr/mm7004e2.htm

This study, like others I've elevated, found that #SARSCoV2 was spreading in contacts less than 15 minutes, and while eating (and other unmasked), less than 5 minutes.

If we keep defining close contact as 15 minutes, we're excluding those who has shorter contacts, especially during unmasked activities, like school breakfast and lunch. Those students & teachers/staff aren't being informed that they may have been exposed, not quarantined...

and if they become a case, aren't being linked back to the exposure that may have occurred at school in a shorter than 15 minute in interval.

The NFL had resources to utilize technology to aid in contact tracing. They refined their definition of highrisk contact and were able to better determine circumstances that placed people at risk for exposure.
They found any mask removal to be high risk, even for a short drink

Imagine the number quarantined from school if we used the NFL's criteria.
Think about the Wisconsin school study and the 184 cases they were unable to link to school spread.
Could the NFLs criteria have helped?