The vaccine used to protect against tuberculosis disease (bacillus calmette-guerin or BCG) also protects against TB infection (mycobacterium) as well as protecting against progression from infection to disease, finds a paper published in the BMJ.

The BCG vaccine has been subject to numerous trials and studies over several decades, which have shown that it has a 60-80% protective efficacy against severe forms of TB in children.

But there is a lack of evidence on whether the vaccine is effective against TB infection. The authors say if BCG is found to protect against infection it will have key implications for the use of BCG in current immunization programs, as well as in the future development of new improved TB vaccines.