BCG vaccination has been shown to give 70%-80% protection against TB (Tuberculosis). Advice on this page is given according to UK recommendations.
TravelHealth.co.uk -- the UK independent travel health site › diseases - Cached - Similar
Note that it is not given in the USA. So an American Child would not have this done.
CDC info at this link: The Role of BCG Vaccine in the Prevention and Control of Tuberculosis in the United States A Joint Statement by the Advisory Council for the Elimination of Tuberculosis and the Advisory Committee on Immunization Practices