Billions in the US and it's part of the infrastructure bill and alot of investment right now. This is a multi-year effort (although IMHO functioning windows should be more normalized instead of going all in on HVAC).

I don't know, but it should pay dividends for generations given it'll probably slow down colds and flus too.

Even things like a box fan in a window are probably significantly more effective than scooby doo masks.

Why should one preclude the other? Defense in depth and all that.

> box fan in a window

That's fine year-round in the south and southwest. Not so much in the rest of the country though.