It gets tiresome always trying to think critically past biases. Haven't done it much on this topic recently. Time consuming, that game.
Other studies have been also been peer reviewed and didn't look at the concentration of the virus in the tykes' nasopharyngeal cavity but at the actual transmission. Note that the Chicago study in the OP actually bears the caveat that it did *not* examine transmission. The other study in the OP probably should, unless buried in the verbiage is the actual claim that they did measure transmission.
In other words, instead of checking the preconditions for the effect and then predicting based on viral concentration, some studies actually look the actual spread--in families, schools, or in other settings. In other words, they've checked the predictions these make. (That's the problem with peer review. A spread of studies hits the pipeline, and they get spit out not always in the expected order.)
That examination can be at a low level--actual contact tracing and correlation with the timing of onset of symptoms--or it can be at a high level, looking at how things like school closures actually seem to affect the transmission rate in general. One's got a lot of individual data points that build up to form the picture; the other approaches it from analyzing variances and engaging in pattern-seeking.
The (peer reviewed) transmission studies are mixed. Most go with an actual low transmission rate, whether building data point by point or digging into higher-level datasets. But not all. That's a bit of a self-contained mystery. I haven't checked back for the last month or so on these. Perhaps that mystery's been resolved.
The other thing that's needed is to try to reconcile the prior studies that actually examined transmission rates with the presence of the virus in the kids at the concentrations noted. If the "self-contained mystery's" resolved to higher concentration, then these studies fit nicely. If not, there's still a reconciling that's needed.
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