A Study to Learn About the Vaccine RSVpreF In Pregnant Participants With HIV and Their Infants

Prior treatment

• Any signs of premature labor with the current pregnancy or having ongoing intervention (medical/surgical) in the current pregnancy to prevent preterm birth.
• Prior pregnancy complications or abnormalities at the time of consent, based on the investigator's judgment, that will increase the risk associated with the participation in and completion of the study, including but not limited to the following:
• Prior preterm delivery at ≤34 weeks' gestation
• Prior stillbirth or neonatal death
• Previous infant with a known genetic disorder or significant congenital anomaly
• Non-HIV-associated congenital or acquired immunodeficiency disorder, or rheumatologic disorder or other illness requiring chronic treatment with known immunosuppressant medications.

Other illness

• Participant with opportunistic infections or malignancy.
• History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention or any related vaccine.
• Preeclampsia, eclampsia, or uncontrolled gestational hypertension.
• Significant bleeding or blood clotting disorder.

Lab values

• History of active chronic viral hepatitis with biochemical evidence of aspartate aminotransferase (AST) or alanine aminotransferase (ALT) values \>5 times the upper limit of normal within 6 months before enrollment.
• Endocrine disorders, including untreated hyperthyroidism or untreated hypothyroidism. This also includes disorders of glucose intolerance (eg, diabetes mellitus type 1 or 2) antedating pregnancy or occurring during pregnancy if uncontrolled at the time of consent.

Other

• Prepregnancy body mass index (BMI) of \>40 kg/m2 . If prepregnancy BMI is not available, the BMI at the time of the first obstetric visit during the current pregnancy may be used.
• Current pregnancy resulting from in vitro fertilization. Participants known to have used clomiphene citrate and/or letrozole with or without intrauterine insemination (IUI) are permitted.
• Current pregnancy complications or abnormalities at the time of consent that will increase the risk associated with the participation in and completion of the study, including but not l limited to the following:
• Placental abnormality.
• Polyhydramnios or oligohydramnios.
• Antituberculosis treatment use currently or at any time during this current pregnancy.
• Infant who is a direct descendant (eg, child or grandchild) of the investigator site staff or sponsor and sponsor delegate employees directly involved in the conduct of the study.

• 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 who are at no known increased risk for complications.
• Confirmed stable HIV disease.
• Current and stable use of antiretroviral therapy(ART) for at least 90 days prior to enrolment.
• Had a fetal anomaly ultrasound examination performed at ≥18 weeks of pregnancy with no significant fetal abnormalities observed.
• Intention to deliver at a hospital or birthing facility where study procedures can be obtained.
• Participant is willing to give informed consent for the participant's infant to participate in the study.
• Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent document (ICD) and in this protocol.
• Evidence of a signed and dated ICD, signed by the parent(s)/legal guardian(s).
• Parent(s)/legal guardian(s) willing and able to comply with scheduled visits, investigational plan, laboratory tests, and other study procedures