One of the ways we catch colds from those that are sick is being in small spaces with them for long periods of time. RVs, even the largest ones, are pretty close quarters. A great way to get air moving is to open up those windows as long as it is not super chilly outside. Open up the door as well.
Anything a sick person comes in contact with becomes a petri dish for the cold virus. Make sure all surfaces are wiped down regularly and be aware of surfaces that like to hold onto and breed bacteria, making us even more sick. Mainly anything with pores and crevices. Some areas to make sure are extra clean include: bath mats, hand towels, bed linens, door knobs, faucet handles, light switches, etc.