BCG vaccine of 2004 the vaccine is given to about 100 million children per year globally. The main use of BCG is for vaccination against tuberculosis. BCG vaccine can be administered after birth intradermally. BCG vaccination can cause a false positive Mantoux test, although a very high-grade reading is usually due to active disease. The most controversial aspect of BCG is the variable efficacy found in different clinical trials, which appears to depend on geography. Trials conducted in the UK have consistently shown a protective effect of 60 to 80%, but those conducted elsewhere have shown no protective effect, and efficacy appears
BCG vaccine 71%. The studies included in this review were limited to those that used interferon gamma release assay. The duration of protection of BCG is not clearly known. In those studies showing a protective effect, the data are inconsistent. The MRC study showed protection waned to 59% after 15 years and to zero after 20 years; however, a study looking at Native Americans immunized in the 1930s found evidence of protection even 60 years after immunization, with only a slight waning in efficacy. BCG seems to have its greatest effect in preventing miliary TB or TB meningitis, so it is still