When you sneeze in Korea, no one says “bless you” or “gesundheit“. In fact, no one says anything at all or even pays any attention to it.
It’s one of the more bizarre things I’ve found about living here, perhaps if only by pointing out how ingrained my own cultural tradition is.
Still, I get very OCD about it and will often say “gesundheit” to my co-teachers if they sneeze. They just think I’m weird.