Systematic review protocol on Bacillus Calmette-Guerin (BCG) revaccination and protection against tuberculosis
Introduction Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis (M.TB) and other species of the Mycobacterium tuberculosis complex.Globally, TB is ranked as the ninth leading cause of death whips and the leading cause of death from a single infectious agent.The bacille Calmette-Guerin (BCG) vaccine has been used globally since 1921