Other factors, such as the immunosuppressive drugs used to prevent rejection after organ transplants, produce an "immune deficiency syndrome" in patients, which also reduces their resistance to infectious disease. Many such effects of medical treatment make infectious diseases more difficult to combat.
而其他如器官移植時用來抑制排斥的免疫抑製藥物，造成病人「免疫缺失症」，也會減低對傳染病的抵抗力，許多醫療後遺症，都使得傳染病越加難以對抗。