Human sneezes, gurgles, wipes face. "I'bve gotta a cold, S'mime O.K." -- Anon Guest
[AN: Nonny, I have no idea what you mean by S'mime there. I can't correct it.]
Of all the terrifying things humanity had invented, the universal winner had to be the Immunoflu. Humanity never could conquer the common cold, nor influenza in its multitudinous strains. But they did tame it. They bio-engineered strains of rhinovirii to improve the immunity of their fellow humans against other, more deadly diseases.
Minor colds could even be created for 'booster shots'.
Manners changed with the invention. With the invention of the immunoflu, the CDC actually encouraged its spread. They finally had a means of spreading an immunity to otherwise isolated groups. Groups who had been in danger from virally-induced extinction. A Human could catch a sniffle for a week or two and be protected against all kinds of diseases that could harm and debilitate others.