While repressing the immune system increases the chance the body will accept an organ, it also increases infection danger. And because the immune system cannot mount a sufficient response to an infection, it is also harder to detect an infection through normal testing. When someone becomes infected from a xenotransplant, that fact might remain unknown until disease symptoms emerge. With a cold or influenza, this generally happens within a couple of days. With a disease such as HIV-AIDS, it may take more than 10 years.
Xenotransplantation makes informed consent impossible.
The full range of risks simply are unknown, not only to patients but also to friends, families, co-workers, and anyone else coming into contact with patients. Others coming into contact with the recipient and becoming infected could also be quarantined. Fortunately, we have promising alternatives. The only way to prevent an infectious agent being passed into a human from a xenotransplant is not to perform the operation. There is simply too much risk.