Research: Reassessing BCG

25 October 2005

The BCG vaccine is thought to protect against the development of tuberculous disease but not infection with Mycobacterium tuberculosis. New research in Istanbul, however, raises doubts about this assumption.

TB is one of the world's commonest infectious diseases. The BCG vaccine has been used in many parts of the world for decades, but its exact value has been hard to judge, as standard diagnostic tests cannot easily distinguish between an M. tuberculosis infection and prior BCG vaccination.

Wellcome Trust Senior Clinical Fellow Dr Ajit Lalvani and colleagues in Oxford have developed a new, more sophisticated test for TB, which is not influenced by BCG. Using this test, his team studied the factors affecting TB infection of children in Istanbul, Turkey.

Surprisingly, BCG-vaccinated children were significantly less likely to be infected with M. tuberculosis. This suggests that BCG is helping to prevent new infections – a finding that could have significant implications for TB control and public health programmes.

External links

• Soysal A et al. Effect of BCG vaccination on risk of Mycobacterium tuberculosis infection in children with household tuberculosis contact: a prospective community-based study. Lancet 2005;366(9495):1443–51. [You need to register to access this link. Registration is free of charge.]