When someone sneezes, you might say Bless you!, at least in English.
In Spanish, I discovered the other day, you say ¡Jesús!. A Welsh friend told me this, and another friend thought it sounded like the Welsh phrase Ga i sws? (May I have a kiss?).
In Welsh you might say Rhad arnat ti!/arnoch chi! (Bless you!), Bendith y Tad! (Blessing of the Father!) or Bendith y mamau! (Blessing of the mothers!).
In French you say À tes/vos souhaits ! (As you wish!).
In German you Gesundheit! (Health!)
What about in other languages?