A condition in which one or more components of the immune system are absent, impaired, or insufficient to provide normal protection against harmful infectious agents.
Immunodeficiency can result from problems that are present from birth (primary immunodeficiency) or develop later because of another condition, infection, medication, cancer, malnutrition, or other factors (secondary immunodeficiency).
Depending on which parts of the immune system are affected, a person may become more susceptible to certain infections, develop infections that are unusually severe or persistent, or have difficulty recovering from infections. Some immunodeficiencies can also affect the body’s ability to respond appropriately to vaccines or other immune challenges.
QUICK FACT
Immunodeficiency does not mean that the immune system is completely absent or inactive. Even a partial impairment of immune function can increase susceptibility to particular infections.
COMMONLY CONFUSED WITH
Autoimmune disease: Immunodeficiency involves inadequate or impaired immune defense, whereas autoimmune disease involves an inappropriate immune response against the body’s own tissues.
SEE ALSO