I can't really think of anything, but I also cannot argue with results.

We did get into habit of handling mail much more carefully. I still wear a mask religiously, I don't touch my face without washing my hands, etc.

And you know what? Maybe it's a coincidence, but nobody has been ill with anything since 2019. That surpassed ALL records we ever had by such a huge margin that it's not even funny any more. Over 3 years without any flu or sniffle, in a house full of people (no kids though, those crotch goblins are just walking infection vectors, and schools are Petri dishes of Nurgle).

Disease has to come from someplace. Taking precautions really does work. Which is why you see doctors sanitizing their hands, wearing masks and PPE, etc. They wouldn't do it if it didn't work.