Oh man, I feel you there. I work in a hospital, and my office is a part of a very small nursing station. My co-workers and I are in constant close quarters. Last year we had a VICIOUS noro outbreak here but I managed not to get it. I think it's because I wipe down everything on my desk with alcohol wipes (I know not all noro is taken care of by alcohol wipes but I do it just to be sure) and wash my hands/don't touch my face. It's really all you can do.