Where I’m from, the person who sneezes often says nothing, unless they’re accidentally sneezing near someone else. Strangers nearby however will say “bless you!

Where I’m from, the person who sneezes often says nothing, unless they’re accidentally sneezing near someone else. Strangers nearby however will say “bless you!” or occasionally “gesundheit!” But yes, I think people who utter the words do so as a quick reaction without much forethought.