Why do we Bless sneezes and not coughs

The phrase god bless you is attributed to pope gregory the great, who uttered it in the sixth.Sneezing was one of the plague's principal symptoms, and pope gregory i is said to have proposed that uttering god bless you after a sneeze would protect the sufferer from death.The 'bless you' phenomenon dates back to as early as 77 bc.Because it is an general belief and people r used to say bless u while sneezing and not while coughing.So wikipedia says it started way back near bible times, but in 590 pope gregory i commanded everyone to say god bless you after someone sneezed because there was a plague going around and sneezing was one of the first symptoms of the plague.While there weren't any explanations given for it, it was obvious people tended to acknowledge sneezes as a sign of good health, deserving of some cheer.

During a plague that occurred in italy in ad 590, sneezing was, or was thought to be, a sign that someone was getting sick with the plague.Why do we bless sneezes but not coughs?What do blessings have to do with sneezes?