IMMUNOCOMPROMISED

In medicine, immunodeficiency (or immune deficiency) is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Most cases of immunodeficiency are either congenital or acquired. A person who has an immunodeficiency is said to be immunocompromised. An immunocompromised person is very vulnerable to opportunistic infections. Boys more often than girls can have immune deficiency. Mostly immune deficiency is recognized in the early ages unless it is an acquired immune deficiency.
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Immunocompromised /im·mu·no·com·pro·mised/ having the immune response attenuated by administration of immunosuppressive drugs, by irradiation, by [more]Immunocompromised - Community and Resources

Adjective
1. unable to develop a normal immune response usually because of malnutrition or immunodeficiency or immunosuppressive therapy
(pertainym) immunological disorder

Having a weakened immune system caused by certain diseases or treatments.