The quest for a new vaccine against tuberculosis.

Tuberculosis (TB) is still one of the deadliest human diseases, killing 1,6 million people each year, mostly in developing countries. The vaccine currently used, Bacille Calmette and Guerin (BCG), is effective in preventing the most severe disseminated forms of disease in children and newborns, but its efficacy against active TB in adults has been challenged by several clinical studies. It is a common opinion that only the development of a new and more effective vaccine against TB would significantly ease the pandemic. In the last few years, the search for a new vaccine has gained a new momentum. New live and attenuated strains of M. tuberculosis, improved recombinant BCG strains and subunit vaccines have been tested in preclinical animal models, and some of them showed promising results. Unfortunately, the lack of immunological correlates of protection makes very difficult to anticipate or foresee the efficacy of any of these new vaccines and only phase III clinical trials, that are expected to start in 2009 and last few years, will tell us the real value of these new prophylactic tools. This review highlights the different strategies that are being implemented for the development of an improved vaccine against TB, the rationale behind them and the potential and feasible vaccination schedules that could be implemented.