Until some more concrete studies on this topic are published, I think the best bet for people on gear is to wash your hands and avoid touching your sinus membranes. The vast majority of adenoviruses enter your system via this route. When I'm on a cycle I take special caution not to touch door handles in public areas - you may look like a weird ass, but if you're a bodybuilder who the hell is going to say anything. However, empirically, I think halo and Anadrol tend to make you more susceptible