When people started washing hands, the primary legitimate concern was ecoli bacteria (i.e. after you go to the bathroom, scrub-a-dub those paws)
It’s evolved (or more accurately: devolved) since then into sanitizing yourself at any given opportunity. This means when you get sick, you really get sick bad and it lasts a long time, which causes the person to use even more sanitation in the future. It’s an unprofitable cycle and it cultivates an attitude of squeamishness towards other human beings.
I’ve noticed less inclination toward rapid fire hand shaking during the “sign of peace” since I’ve started attending RC services again. I don’t know if it indicates heightened awareness of the contagion of disease via hands (which is true of a vast number diseases-- I teach a course in medical microbiology!) or it’s simply that I moved several hundred miles away from where I used to live, and I"m in a more conservative area. Anyway, most people in the RC churches around here seem content to fold their hands, make eye contact, smile and bow, rather than rush about the pews. Now if only the Anglican churches would follow suit!
And yes, kissing an object that someone else has just kissed, or more importantly touched,
could spread infection. E. coli, haemophilus influenzae, viral flu, shigellosis, Corynebacterium sp., diphtheria, pertussis, rhinovirus, pneumonic plague, MERS, MRSA, and many more.
Sorry. That’s what happens when you teach medical microbiology to middle school kids! By the end of the course we have a long list of “don’ts:” don’t shake hands, don’t kiss, don’t swim, don’t play with squirrels, don’t pet armadillos at the petting zoo, don’t eat the food at picnics, don’t open letters from people you don’t know, etc. etc. And the list of “do’s” is empty.