Common Variable Immunodeficiency (CVID) is a primary immunodeficiency disorder characterized by low levels of immunoglobulins, which are antibodies that help the body fight infections. Individuals with CVID often experience recurrent infections, particularly in the respiratory and gastrointestinal tracts, due to their weakened immune system. The exact cause of CVID is not well understood, but it can lead to complications such as autoimmune diseases and an increased risk of certain cancers. Diagnosis typically involves blood tests to measure antibody levels, and treatment often includes immunoglobulin replacement therapy to help boost the immune response.