Antituberculous vaccine development: a perspective for the endemic world

Several new antituberculous vaccine candidates that are effective against primary infection in preclinical animal models have now entered the early phases of clinical trials. Many of these clinical trials involve subunit vaccines, recombinant bacillus Calmette–Guérin (BCG), or improvement of BCG immunity by boosting with subunit vaccines or recombinant viral vectors expressing immunodominant TB antigens. The burning question at this stage is: will the current vaccines be effective in the endemic world where the diverse and complex challenges of TB exist? These challenges include protection of those individuals who are already vaccinated with BCG, those already exposed to environmental mycobacteria and those infected with latent TB or HIV. This review focuses on the available BCG vaccine, new TB vaccines in the pipeline and what type of vaccines are actually needed in high-burden endemic countries.