How do diseases spread? kissing is one factor(kissing on the mouth,which is not under the threat of being banned is actually more dangerous a transmitter than the 'kiss each-other's cheeks greeting' that is ), talking to a person(saliva is airborne it travels into the air as you speak irrrespective of whether you 'spit' while you talk or not), touching(especially with unwashed hands), sex, using the same needles/sharp objects and well, virtually any form of contact. You can't 'ban' everything.

During the S.A.R.S threat people were told to wear gas masks: Something that would be infinitely more effective than a ban on tradition, as it protects people from sneezes and coughs (acts that can otherwise not be controlled/contained/prevented).

Children can spread the disease with heart-shaped cards just as easily as kissing cheeks. They will obviously handle the cards and if they've got a cold (since children aren't exactly hygiene-conscious) they will not wash their hands every-time the sneeze. Thus the replacement for the greeting is no better.

Kissing,hugging,stroking,caressing and/or any other physical gesture of warmth creates a sense of well-being/security that helps patients heal faster(accelerates the healing process). All diseases have a psycho(psychological) and soma(physical) element. Some diseases are called psychosomatic since the physical symptoms are caused SOLELY by psychological factors. However I repeat 'ALL' diseases have these elements. People 'feel' better when they are greeted warmly and affectionately.

Touch therapy and Reiki are both effective healing methods for a variety of diseases^[1]

So, on the flip-side the greeting could help alleviate the disease and its symptoms.

And this might also explain why France is less affected than Britain.^[2]

1. ^ http://healing.about.com/od/touchtherapy/Touch_Therapy.htm
2. ^ http://www.telegraph.co.uk/news/worldnews/europe/france/6155768/France-facing-la-bise-ban-over-swine-flu-fears.html