Seems stupid all right but there have been differences in countries due to cultural behaviours including speech. There’s a reason it spread so fast in Italy (kissing on cheeks, over-expressive when speaking to the point of spittle etc.) but not so much in Japan where people don’t even shake hands. Surely the language most likely to spread any disease would be European Spanish though - I can’t think of another language in which the lack of a lisp can be considered a speech impediment.