Study of a Group B Streptococcus Vaccine in Pregnant Women Living With HIV and in Pregnant Women Who do Not Have HIV

Inclusion Criteria: 1. Participants at least 18 years old and not older than 40 years of age. 2. Pregnant women who are between 26 weeks and 30 weeks (inclusive) gestation on the planned day of vaccination with a singleton, uncomplicated pregnancy. Gestational age to be determined on the following hierarchal basis with guidance to the GAIA (Global Alignment of Immunisation Safety Assessment in pregnancy) criteria: 1. ultrasound estimate of gestational age, 2. date of last menstrual period 3. fundal height 3. HIV status to be based on rapid, confirmatory test, unless a documented test of the participant being sero-positive for HIV and history documented in the notes. 4. Women living with HIV, HIV viral load \<1000, on antiretroviral therapy for at least 3 months prior to screening and clinically well. 5. Expected to be available for the scheduled clinic visits for the duration of the study, agree to be contacted by telephone during study participation, and is willing to give parental consent for her infant to participate in the study Exclusion Criteria: 1. Women who are HBSAg and/or HCV (hepatitis C virus) positive 2. Women who test positive for syphilis as per standard testing 3. Women knowingly carrying, at screening, a malformed or genetically abnormal foetus based on ultrasound 4. Women who have experienced a previous stillbirth prior to going into labour 5. Women with placenta previa 6. Women with documented chronic or pregnancy induced hypertension at screening 7. Women with 1+ protein in urine and hypertension defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg) at ≥20 weeks of gestation in a woman with a previously normal blood pressure 8. Women with \>1+ of protein in urine (regardless of blood pressure) 9. Women with gestational, type 1 or type 2 diabetes. 10. Women with glycosuria on dipstick 11. Women known to be allergic to any components of the vaccine, who are known to be allergic to aluminium or have had an allergic reaction to any previous vaccination. 12. Women with HIV viral load \>1000 at screening. 13. Women living with HIV who have been on antiretroviral therapy for less than 3 months prior to screening. (Women who are diagnosed with HIV between screening and dosing will not be eligible.) 14. Women with history or presence of significant cardiovascular disease, pulmonary, hepatic, gallbladder or biliary tract, renal, haematological, gastrointestinal, endocrine, immunologic, dermatological, neurological, psychiatric, autoimmune disease, cognitive disorder or current infection and significant illness 4 weeks prior to randomization. 15. Women with current or history of drug or alcohol abuse within the last two years. 16. Women who have received a vaccine within 28 days of receiving the first dose of GBS NN/NN2 or placebo or who expect to require vaccination during the course of the study. (Vaccines recommended for administration during pregnancy e.g. tetanus toxoid, pertussis and influenza are permitted. Administration of concurrent vaccines must not be within 7 days of investigational vaccine.) 17. Women who have a fever (axillary temperature \>37.9°C) on the day of dosing or have had an acute infection in the 7 days before dosing. 18. Women who have any bleeding disorders that prolong the bleeding time. 19. Women who are receiving immunosuppressive medication, including systemic steroids (inhaled and topical steroids are acceptable). 20. Women who have received blood or blood products and/or plasma derivatives or any immunoglobulin preparations in 12 weeks preceding screening. 21. Women with severe anaemia, haemoglobin \< 9g/dL (90 g/L) as per Sheffield grading system ( \> Grade 1) 22. Women who are currently breast feeding 23. Women who are part of the study personnel or a close family member of study personnel. 24. Women who in the opinion of the investigator are not suitable to participate in the study. 25. Concurrent participation in another clinical trial during which subject will be exposed to an investigational product .