Current trends in tuberculosis vaccine.

Despite the global efforts made to control tuberculosis (TB) and the large number of available new anti-TB drugs, TB still affects one-third of the world population. The conventional vaccine bacille Calmette-Guérin (BCG) shows varying efficacy in different populations, and there are safety issues in immunocompromised patients. Hence, there is an urgent requirement for a new and better TB vaccine candidate than BCG. There are several alternate vaccines available for TB such as DNA, subunit, adjuvant, and live-attenuated vaccines. Use of auxotrophic vaccine is an emerging technology. Newer vaccine technologies include vaccine delivery methods such as adenovirus- and cytomegalovirus (CMV)-based vector delivery, chimeric monoclonal antibody, single-chain fragment variable, RNA-lipoplexes, and nanoparticle-based technology. Based on its application, TB vaccines are classified as conventional, prophylactic, booster, therapeutic, and reinfection preventive vaccines. Currently, there are 12 vaccine candidates in clinical trials. In this review, we have briefly discussed about each of these vaccines in different phases of clinical trials. These vaccines should be analyzed further for developing a safe and more efficacious vaccine for TB.