What is immunodeficiency?
Immunodeficiency refers to a group of diseases in which the immune system does not function normally. A normal immune system will attack what is seen as a foreign invader, like bacteria and viruses. When the immune system does not work properly, a person is more likely to suffer from frequent and longer-lasting infections, often from organisms that usually don’t make most people sick. Most cases of immunodeficiency are acquired (“secondary”), but some people are born with defects in the immune system (a “primary” immunodeficiency).