This is a Phase 1b/2a, double-blind, randomized, BCG-controlled, dose-escalation safety and immunogenicity study in 144 healthy adults with and without LTBI. All participants will have received previous BCG vaccination in infancy. The investigational product is 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 meeting the inclusion/exclusion criteria will be randomized within a study cohort to receive a single dose of MTBVAC or BCG revaccination administered intradermally on Study Day 0. The study will be conducted at one site in South Africa. Participants will be enrolled into one of eight cohorts and followed for safety and immunogenicity endpoints through Study Day 365. The estimated time to complete enrolment is approximately 12 months.~Cohorts 1-8 will include 72 QFT-negative (Cohorts 1-4) and 72 QFT-positive (Cohorts 5-8) participants. Participants will be randomized within each cohort, to receive either MTBVAC (N=96) or BCG (N=48). The cohorts will be enrolled as described in the protocol, as long as no pausing/stopping rules are triggered
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.