[timr]

> That said, if the massive reduction in flu cases isn't a result of some or all of our Covid efforts, it'd be a hell of a coincidence.

Mmmm...I wouldn't go that far. Like I said, my current preferred theory involves schools, but other plausible theories involve things like mutual inhibition: infection with one virus somehow interferes with infection by the other.

We have some evidence of this happening in the past. Strains of influenza have abruptly vanished due to this phenomena.

Certainly, I'd agree that this is interesting (which is pretty much where I end up on this, vs. the OP, who thinks the matter is settled.)

[clairity]

more generally, it's likely due to greater (indoor) distancing, of which school closures is a subset. the slight differences in transmission characteristics between flu and covid (also represented as differential r0) likely makes flu relatively more susceptible to reduction by distancing.

and distancing is a first-order mitigation that overwhelms the effects of inferior/ineffective mitigations like cleaning, sanitizing, mask-wearing, extra ventilation, etc. those secondary mitigations can make more of a difference when we want to pack it in, like at a movie theater, but otherwise they don't do much because those circumstances are relatively rare.

folks just don't want to accept such a simple answer because it means there's not much to hang their anxiety on, and that cognitive dissonance is unacceptable, as it always is.