Safety and Immune Responses After Vaccination With Two Investigational RNA-based Vaccines Against Tuberculosis in BCG Vaccinated Volunteers

This is a two-part randomized, placebo-controlled, observer-blind, safety and dose-finding Phase Ib/IIa study. This study will evaluate up to four dose levels of the BNT164 investigational vaccines (BNT164a1 and BNT164b1) to select a safe and tolerable dose in a three-dose schedule.

This study includes: Part A (Phase Ib) and Part B (Phase IIa).

In Part A, enrollment for BNT164a1 and BNT164b1 will be conducted independently and in parallel. Part A of the study will enroll participants into four dose groups per investigational medicinal product (\[IMP\] i.e., BNT164a1 or BNT164b1) who will be stratified by interferon gamma release assay (IGRA) status and then randomized 5:1 for BNT164 (BNT164a1 or BNT164b1):placebo. This part of the study will use a staggered dose escalation schema, i.e., enrollment into the next higher dose level is done sequentially and subject to safety data from the previous dose levels, with sentinel participants for Dose 1 in all dose groups.

Part B of this study is a safety expansion in human immunodeficiency virus (HIV)-negative participants of up to two dose groups per IMP (BNT164a1 or BNT164b1) + placebo selected based on the safety and immunogenicity data from Part A. Participants will be randomized 3:3:3:3:1 to up to four dose groups of BNT164 (BNT164a1 or BNT164b1):placebo.

In both Part A and Part B, participants will undergo a three-dose injection schedule with approximately 8 weeks between the first and second dose and approximately 16 weeks between the second and third dose.