Social Etiquette around Snotty Nose kids

I mean this question a lil bit tongue-in-cheek, but also genuinely curious...

Dads, what is the social etiquette around other's snotty nose kids?

Let me explain. I was at a play group with my son (16mth old), and this random kid comes up to us with snot full-on volcanoeing out of his nose and trying to hand us toys.

I know, I know, germs are unavoidable. I don't want to be over-the-top protective. But I also don't want to get sick. Work is hella busy right now, I cannot afford days off.
Infact, a few days have passed and pretty sure I've caught something - can feel the throat build up.

All that considered - What the heck is the social etiquette around other's snotty nose kids? 😂😂😂