Study to Evaluate the Safety, Tolerability and Immunogenicity of Three Doses of GBS Vaccine in Elderly Participants

Inclusion Criteria: 1. Participants aged 55 to 75 years. 2. Body mass index (BMI) ≥18 and ≤30 kg/m2 for healthy participants, ≥ 30 to ≤45 kg/m2 for obese participants and ≥18 to ≤45 kg/m2 for type 2 diabetic participants. 3. Able to voluntarily provide written informed consent to participate in the study. 4. Female participants must be post-menopausal. 5. Participants capable and willing to follow trial schedule and procedures. Exclusion Criteria: 1. Participants who have received a GBS vaccine previously. 2. Participants with history or presence of significant (as evaluated by the investigator) cardiovascular disease, pulmonary, hepatic, gallbladder or biliary tract, renal, haematological, gastrointestinal, endocrine, immunologic, dermatological, neurological, psychiatric, autoimmune disease or current infection. NOTE: Patients with type 2 diabetes are to be recruited for Cohort 3 and Cohort 4. 3. Laboratory values at screening which are deemed by the investigator to be clinically significantly abnormal. 4. Current or history of drug or alcohol abuse per investigator judgement. 5. Positive for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C. 6. Participants currently participating in a clinical trial. 7. Participants receiving an investigational drug, vaccine or device during the 90 days preceding the initial dose in this study. 8. Any significant illness during the 4 weeks preceding the vaccination visit, per investigator judgement. 9. Participants with a history of severe allergic reactions after previous vaccination. 10. Participants who have received any vaccine within 30 days of first IMP administration, or who are planning to receive any vaccine (eg, travel vaccines) up to 30 days after each vaccination. NOTE: Exceptions could be made for emergency vaccinations (eg, tetanus) or vaccination campaigns (eg, SARS, CoV-2 or influenza) which will be permitted not less than 7 days before or after study vaccination. 11. Participants receiving immunosuppressive therapy or immunoglobulins in the 6 months prior to screening. 12. Participants within a 7-day period after an acute infection in the 7 days preceding vaccination, as per investigator judgement, or with fever (oral temperature \>37.9°C) in the 72 hours preceding vaccination. 13. Participants who have received antipyretics/analgesics treatment within 72 hours prior to dosing. 14. Participants on chronic medications that are likely to affect the assessments specified in the protocol (eg, anticoagulant therapy, systemic steroids). NOTE: Chronic medications such as antihypertensives, bronchodilators, statins that do not affect the immune system, will be permitted and allowed to continue during the study at the discretion of the investigator. Treatment for diabetes will be continued as required for the diabetic participants recruited. Non-steroidal anti-inflammatory drugs or paracetamol will be permitted for the treatment of headache or other symptoms during the study. Use of over the counter (OTC) vitamins and dietary supplements is allowed. 15. Participants with skin defects and/or tattoos at the proposed site of vaccine administration. 16. Donation of blood or blood products within 90 days prior to first study vaccination. 17. Participants who, in the opinion of the Investigator, are unsuitable for participation in the study. 18. Involvement in the planning and/or conduct of the study (applies to both Sponsor personnel and/or personnel at the study centre or Clinical Research Organisation \[CRO\]).