[Dog Gone]

It seems possible to me that infected people who are not yet showing symptoms are indeed contagious, but not at their peak in terms of danger to others.

Someone may not have developed the dry cough that is probably the biggest culprit in spreading the virus, but people who are not ill often cough and sneeze everyday over some minor irritant. These "routine" expulsions of air could very well be laced with the virus, and nobody thinks a thing about it.

[CathyRyan]

But most of the information that the epidemiologists have been able to put together suggests that the period of contagion may begin with the onset of the very earliest symptoms of a viral infection, so our guidance is based on this assumption

http://www.freerepublic.com/focus/f-news/881127/posts