I literally wrote what I suggested and what you're asking: mandate air purifiers (and ventilation/AC in general...) for public and educational buildings. Additionally to that and specially for the US: introduce unlimited paid sick time, just like every other Western country already has.
And maaaaybe introduce by law a ban on knowingly sending sick kids to kindergarten/schools. It's utterly insane to watch every year how the weeks after major holidays are filled with "colleague X is out sick, caught a bug from their kids". If there is one thing every parent in my social circle is cursing about, it is all the tons of bugs their kids bring home from school because other parents can't be arsed to let their kid spend a few days at home watching TV - and it's not just covid. Lice, ordinary flu, hand-foot-mouth or whatever it's called in English, measles, ordinary fever, vomit/diarrhea...
> For trying to avoid an illness at all costs that not only wasn't particularly dangerous to begin with for the general population
In the US alone, 1.2 million people died of COVID. That's far from "wasn't particularly dangerous".
> but also is very much manageable today, particularly considering that most people are vaccinated now (or at least have the opportunity to get vaccinated).
Vaccines aren't perfect, even including them about 3-5% of the infected have a risk for debilitating long-covid (i.e. ME/CFS). It's not a gamble I want to take part in.