Primary immunodeficiency with post-measles-mumps-rubella vaccine viral infection is a rare primary immunodeficiency due to a defect in innate immunity disorder characterized by selective susceptibility to viral infections, particularly after systemic challenge with live viral vaccines, such as the measles, mumps and rubella (MMR) vaccine. Patients present severe, potentially fatal, manifestations to viral illness, including encephalitis, hepatitis and pneumonitis. The disease is primary immunodeficiency with post-measles-mumps-rubella vaccine viral infection (MONDO_0014715). Also known as: IMD44, immunodeficiency 44, immunodeficiency type 44, primary immunodeficiency with post-MMR vaccine viral infection.