A second-generation anti TB vaccine is long overdue

Mycobacterium bovis BCG vaccine significantly reduces the risk of tuberculosis by 50% and continues to be used to prevent tuberculosis around the world. However, it has been shown to be ineffective in some geographical regions. The existence of different BCG strains was described more than 60 years ago, these vary in their antigenic content but the genetic mutations in BCG strains have yet been shown to affect their protection. After the declaration of tuberculosis as a global emergency in 1993, current research attempts to develop a novel more-effective vaccine. Using new technologies, recombinant, auxotroph, DNA, subunit and phylogenetically closely related mycobacteria, naturally or genetically attenuated, have been used as vaccines in animal models, but their protective efficacy, is less than that offered by the current BCG vaccine. Today it is mandatory that a major effort be made to understand how different BCG vaccine strains influence immune response and why in some cases vaccines have failed, so we can rationally develop the next generation of tuberculosis vaccines to reduce the prevalence from 10% to less than 2 % for developed countries.