BEATRIX: A Study to Learn About a Group B Streptococcus Vaccine in Healthy Pregnant Women and Their Babies

Key Inclusion criteria- Maternal: * Healthy pregnant women ≤49 years of age who are between 24 0/7 and 36 0/7 weeks of gestation on the day of planned vaccination, with an uncomplicated, singleton pregnancy, and who have no known increased risk of complications. * Had a fetal anomaly ultrasound examination with no significant fetal abnormalities observed. * Documented negative human immunodeficiency virus (HIV) antibody test, syphilis test, and hepatitis B virus (HBV) surface antigen test during this pregnancy and prior to randomization. * Capable of giving personal signed informed consent. * Willing to give informed consent for her infant to participate in the study. Key Exclusion criteria- Maternal: * Prepregnancy body mass index (BMI) of \>40 kg/m2. * Current pregnancy complications or abnormalities that may increase the risk associated with the participation in and completion of the study. * Prior pregnancy complications or abnormalities that, based on the investigator's judgment, may increase the risk associated with the participation in and completion of the study. * History of microbiologically proven invasive disease caused by GBS in the current pregnancy. * A known or suspected infection during the current pregnancy that may increase the risk of complications in pregnancy (eg, active tuberculosis, syphilis, primary genital herpes simplex, malaria). Key Inclusion criteria- Infant Participants \- Evidence of a signed and dated ICD signed by the parent(s)/legally authorized representative or legal guardian Key Exclusion Criteria - Infant Participants: \- Children or grandchildren who are direct descendants of investigator site staff or sponsor and sponsor delegate employees directly involved in the conduct of the study. Key Exclusion Criteria - Infant immunogenicity subset Participants: \- Children with a known or suspected contraindication to any vaccine administered in the infant vaccine immunogenicity subset. Refer to the study contact for further eligibility details