Persistent Bacillus Calmette-Guerin Reaction: A Potential Clue to Underlying Immune Deficiency.

Bacillus Calmette-Guerin (BCG) vaccine complications in patients with severe combined immunodeficiency (SCID) have been well documented in the literature. We present a case in which the BCG vaccine was administered to an infant who was later diagnosed with SCID and presented with worsening localized BCG reaction upon arrival in the United States. Although the BCG vaccine is not routinely administered in the United States, it is important for physicians to be aware of potential complications of BCG vaccination since prompt treatment can be lifesaving.