MTBVAC at four dose levels: 5 x 10^3 CFU, 5 x 10^4 CFU, 5 x 10^5 CFU, and 5 x 10^6 CFU. The active control is BCG (5 x 10^5 CFU). Participants will receive a single dose of MTBVAC or BCG revaccination administered intradermally on Study Day 0.