A Pivotal Safety and Immunogenicity GBS-NN/NN2 Vaccine Maternal Immunisation Trial

The main objective of the Phase 2 part of the trial is to assess the immunogenicity of GBS-NN/NN2 vaccine at birth in infant participants and to determine the occurrence of serious adverse events (SAEs) and adverse event of special interest (AESIs) after GBS-NN/NN2 vaccine administration compared to placebo, in both maternal and infant participants. The main objective of the Phase 3 part of the trial is to assess the ability of GBS-NN/NN2 vaccine to induce functional antibody titres protective against invasive GBS (iGBS) early-onset disease (EoD) in infant participants, to assess the ability of GBS-NN/NN2 vaccine to induce functional antibody titres protective against iGBS late-onset disease (LoD) in infant participants and to determine the occurrence of SAEs and AESIs after GBS-NN/NN2 vaccine administration compared to placebo, in both maternal and infant participants.

Inclusion Criteria: 1. Maternal participant carrying a normal singleton pregnancy at 24 (-2/+3) weeks GA at the planned time of the first trial vaccination. GA must be based upon below criteria: * Last menstrual period (LMP) date corroborated by first or second trimester ultrasound examination, i.e., at or before screening. * First or second trimester ultrasound examination only, if LMP is unknown/uncertain. 2. Participants ≥18 to ≤49 years of age with a body mass index (BMI) of \>17.5 to \