* for 6 months after delivery of their baby (around 10 months in total). Pregnant participants will have at least 5 planned visits in this study. Infant participants: All eligible babies born to enrolled mothers will be followed up from birth for up to 6 months. Infant participants will have at least 3 study visits, with some site visits allowed to happen via home visits or over the telephone. conditions: Respiratory Syncytial Virus studyType: INTERVENTIONAL phases: PHASE3 allocation: RANDOMIZED interventionModel: PARALLEL primaryPurpose: PREVENTION masking: QUADRUPLE maskingDescription: This is a double-blinded, placebo-controlled study whoMasked: PARTICIPANT whoMasked: CARE_PROVIDER whoMasked: INVESTIGATOR whoMasked: OUTCOMES_ASSESSOR count: 330 type: ESTIMATED name: RSVpreF vaccine name: Placebp measure: Maternal Participants Primary Safety - The proportion of participants reporting systemic reactions measure: Maternal Participants Primary Safety - The proportion of participants reporting local reactions measure: Maternal Participants Primary Safety - The proportion of participants reporting Adverse Events (AEs) measure: Maternal Participants Primary Safety - The proportion of participants reporting Adverse Event of Special Interests (AESIs) measure: Maternal Participants Primary Safety - The proportion of participants reporting Serious Adverse Events (SAEs) measure: Infant Participants Primary Safety - The proportion of participants reporting Specific Birth Outcomes measure: Infant Participants Primary Safety - The proportion of participants reporting Adverse Events (AEs) measure: Infant Participants Primary Safety - The proportion of participants reporting SAEs and Newly Diagnosed Chronic Medical Conditions (NDCMCs) measure: Maternal Participants: Secondary Immunogenicity - GMT of NTs for RSV A and RSV B measure: Maternal Participants: Secondary Immunogenicity - GMFR of NTs for RSV A and RSV B sex: ALL minimumAge: 0 Years maximumAge: 49 Years stdAges: CHILD stdAges: ADULT facility: Synergy Biomed Research Institute status: NOT_YET_RECRUITING city: East London state: Eastern CAPE zip: 5241 country: South Africa lat: -33.01529 lon: 27.91162 facility: Josha Research status: NOT_YET_RECRUITING city: Bloemfontein state: FREE State zip: 9301 country: South Africa lat: -29.12107 lon: 26.214 facility: Worthwhile Clinical Trials status: RECRUITING city: Benoni state: Gauteng zip: 1500 country: South Africa lat: -26.18848 lon: 28.32078 facility: REIMED Reiger Park status: NOT_YET_RECRUITING city: Boksburg state: Gauteng zip: 1459 country: South Africa lat: -26.21197 lon: 28.25958 facility: Wits RHI status: NOT_YET_RECRUITING city: Johannesburg state: Gauteng zip: 2001 country: South Africa lat: -26.20227 lon: 28.04363 facility: University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA) status: NOT_YET_RECRUITING city: Johannesburg state: Gauteng zip: 2013 country: South Africa lat: -26.20227 lon: 28.04363 facility: Wits VIDA Nkanyezi Research Unit status: NOT_YET_RECRUITING city: Johannesburg state: Gauteng zip: 2093 country: South Africa lat: -26.20227 lon: 28.04363 facility: Wits VIDA Nkanyezi status: NOT_YET_RECRUITING city: Johannesburg state: Gauteng zip: 2093 country: South Africa lat: -26.20227 lon: 28.04363 facility: Botho Ke Bontle Health Services status: RECRUITING city: Pretoria state: Gauteng zip: 0184 country: South Africa lat: -25.74486 lon: 28.18783 facility: Setshaba Research Centre status: NOT_YET_RECRUITING city: Tshwane state: Gauteng zip: 0152 country: South Africa facility: Qhakaza Mbokodo Research Clinic status: NOT_YET_RECRUITING city: Ladysmith state: Kwazulu-natal zip: 3370 country: South Africa lat: -28.55874 lon: 29.77896 facility: Gole Biomed Research Centre status: RECRUITING city: Polokwane state: Limpopo zip: 0734 country: South Africa lat: -23.90449 lon: 29.46885 facility: MRC Unit on Child And Adolescent Health status: NOT_YET_RECRUITING city: Cape Town state: Western CAPE zip: 7700 country: South Africa lat: -33.92584 lon: 18.42322 hasResults: False