Disseminated Bacille Calmette‐Guérin infection in a patient with severe combined immunodeficiency caused by <i>JAK3</i> gene mutation

Bacille Calmette-Guérin (BCG), a live attenuated vaccine prepared using Mycobacterium bovis, can prevent tuberculosis in children and is routinely administered to infants in China and many other countries. A serious complication following vaccination is disseminated BCG infection. The risk is greatly increased in patients with severe combined immunodeficiency disease (SCID), a syndrome characterized by deficiency of both humoral and cellular immunity. We report a case of disseminated BCG infection in an infant with SCID caused by two novel janus kinase 3 (JAK3) gene mutations.