Current status of new tuberculosis vaccine in children.

Pediatric tuberculosis contributes significantly to the burden of TB disease worldwide. In order to achieve the goal of eliminating TB by 2050, an effective TB vaccine is urgently needed to prevent TB transmission in children. BCG vaccination can protect children from the severe types of TB such as TB meningitis and miliary TB, while its efficacy against pediatric pulmonary TB ranged from no protection to very high protection. In recent decades, multiple new vaccine candidates have been developed, and shown encouraging safety and immunogenicity in the preclinical experiments. However, the limited data on protective efficacy in infants evaluated by clinical trials has been disappointing, an example being MVA85A. To date, no vaccine has been shown to be clinically safer and more effective than the presently licensed BCG vaccine. Hence, before a new vaccine is developed with more promising efficacy, we must reconsider how to better use the current BCG vaccine to maximize its effectiveness in children.