BCG vaccine
There has been ongoing debate about the effectiveness of BCG vaccination for a number of years. Effectiveness in different studies varies between 0-80%. Despite that, protection against disseminated childhood tuberculosis seems to be quite high.

Partly because of this, BCG policies in different countries vary between no immunisation (USA), high risk immunisation at birth with universal immunisation at 13 (UK), universal neonatal immunisation (Indian subcontinent and much of Africa) and multiple immunisation (much of Eastern Europe).

The vaccine seems more effective in trials in temperate rather than tropical areas. Protection induced by BCG seems to improve with increasing distance from the equator. In a large randomised controlled trial in Madras, southern India and a large observational study in Malawi, BCG was no better than saline.

Alternatives to BCG have been sought so far without effect, but the sequencing of the genome of M.tuberculosis increases the possibility of DNA and subunit vaccines. The difficulties of devising and testing antigens or bacteria that will provide immunity against a facultative intracellular organism with the ability to remain dormant for years are not to be underestimated.

Images from Greece...