Common variable immunodeficiency (CVID) comprises a heterogeneous group of diseases characterized by a significant hypogammaglobulinemia of unknown cause, failure to produce specific antibodies after immunizations and susceptibility to bacterial infections, predominantly caused by encapsulated bacteria. The disease is Monarch Disease Ontology identifier MONDO_0015517 (common variable immunodeficiency). Also known as: CVID, Common Variable Immune Deficiency, common variable agammaglobulinemia, idiopathic immunoglobulin deficiency, primary antibody deficiency, primary hypogammaglobulinemia, secondary hypogammaglobulinemia, sporadic hypogammaglobulinemia.