Using a condom in case of Cancer and Hepatitis

BS"D

Shalom Rav,

I would like to pose the following question. A friend of mine was recently diagnosed with a highly malignant Non-Hodgkin lymphoma, R"L. He started to undergo chemotherapy. Now, during the course of diagnostic procedures, which preceded the start of the therapy, he was found out to be infected with hepatitis C; his wife is not.

Now, given the danger of transmitting the virus of hepatits C during marital relations, is the usage of condomes allowed? If not, (a) does the presumed non-viability of the sperm during the chemotherapy give some room for being more lenient concerning hashchatath zera, (b) how kann marital relations be maintained in the long run, given the fact that hepatits C cannot be healed at present?

Thank you very much in advance.