I am a nurse that works on a cancer/CF/overflow of same day gyno surgeries. The only risk of the chemotherapy affecting someone (other than the intended patient) is by urine and depending on the type of chemo, blood. We monitor our patients intake/output so we wear special chemo gloves when we dump the urine of chemo patients, and when we draw their blood. Other than that, they are free to roam around the room, ward or hospital as allowed by the doctor and per their own tolerance level, Even while the chemo is hanging on their IV pole.
A persons immuen system is SEVERELY lowered on come occasions immediately after the chemo treatment, you might hear neutropenic fever. It's when the patients nutrophil counts fall below a certain number (different hospitals have different scales) and in come cases are zero. They start feeling very weak, feverish and all together crappy. AT that point it is essential for them to return to the hospital and be admitted so they can be put on antibiotics to control the neutro fever. The recommendation by the second poster of wearing a mask is a good idea, for you, the family members and the patient. Of course, it is a personal decision. One of our patients wears a mask Everywhere Post chemo (and while on it after the first few days as well) just as a precaution. She also requests that anyone entering her room wears one as well, even if she has one on. she has only been back 1 time for neutro fever, I think her precautions might have something to with it.
So all in all, the Chemo recipient is actually more at risk for contracting something because their immune system is so low after chemo, put proper (and as some might say anal) precautions usually prevent that. Good luck
Julie (Wife to Mark 24 w/CF)