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

A PHASE 3, RANDOMIZED, DOUBLE-BLINDED, PLACEBO-CONTROLLED TRIAL TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF RESPIRATORY SYNCYTIAL VIRUS (RSV) PREFUSION F SUBUNIT VACCINE IN PREGNANT PARTICIPANTS LIVING WITH HIV AND THEIR INFANTS

The purpose of the study is to learn about the safety and immune activity of the RSVpreF vaccine. It will be studied in infants born to mothers living with HIV. These infants may have higher chances of getting sick or dying due to RSV infection. Respiratory Syncytial Virus (RSV) is a common type of virus (germ) that can cause severe illness (airway diseases), where medical help is needed. Vaccines help your body make antibodies which help fight against diseases. The antibodies are substances your body uses to fight off an infection. The antibodies can be passed to the infant through the placenta of the mother.

The study will look at the safety, tolerability, and immune activity in mothers and their infants.

This study is seeking pregnant women who are:

• Less than or equal to 49 years old and have HIV (Human immunodeficiency virus -
• Receiving standard medical care during the pregnancy
• Do not have syphilis (bacterial sexually transmitted disease), Hepatitis B Virus ((HBV) liver infection), Tuberculosis ((TB) bacterial lung infection).
• Have been on stable (anti-retroviral) HIV treatment for more than or equal to 90 days.
• agree to be present for all study visits, procedures, and blood draws.

Participants will either receive:

• RSVpreF vaccine
• A placebo. A placebo does not have any medicine it but looks just like the study vaccine.

Pregnant participants will be involved in the study from:

• consent during their current pregnancy, and
• 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.

Study Overview

• Status: Completed
• Conditions: Respiratory Syncytial Virus
• Intervention / Treatment: Biological: RSVpreF vaccine; Biological: Placebp

• Study Type: Interventional
• Enrollment (Actual): 681
• Phase: Phase 3

Contacts and Locations

Study Locations

• South Africa
  • Eastern Cape
    • East London, Eastern Cape, South Africa, 5241
      • Synergy Biomed Research Institute
  • Free State
    • Bloemfontein, Free State, South Africa, 9301
      • Josha Research
  • Gauteng
    • Benoni, Gauteng, South Africa, 1500
      • Worthwhile Clinical Trials
    • Boksburg, Gauteng, South Africa, 1459
      • REIMED Reiger Park
    • Johannesburg, Gauteng, South Africa, 2001
      • Wits RHI
    • Johannesburg, Gauteng, South Africa, 2013
      • University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)
    • Johannesburg, Gauteng, South Africa, 2093
      • Wits VIDA Nkanyezi Research Unit
    • Pretoria, Gauteng, South Africa, 0184
      • Botho Ke Bontle Health Services
    • Pretoria, Gauteng, South Africa, 0152
      • Setshaba Research Centre
  • KwaZulu-Natal
    • Ladysmith, KwaZulu-Natal, South Africa, 3370
      • Qhakaza Mbokodo Research Clinic
  • Limpopo
    • Polokwane, Limpopo, South Africa, 0699
      • Gole Biomed Research Centre
  • Western Cape
    • Cape Town, Western Cape, South Africa, 7700
      • MRC Unit on Child And Adolescent Health
    • Cape Town, Western Cape, South Africa, 7750
      • Gugulethu Green Clinic
    • Worcester, Western Cape, South Africa, 6850
      • FAMCRU - Worcester

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

Description

Key Inclusion Criteria - Maternal Participants

• 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.

Key Inclusion Criteria - Infant Participants

• 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

Key Exclusion Criteria - Maternal Participants

• 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.
• Participant with opportunistic infections or malignancy.
• 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.
• 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.
• 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:
• Preeclampsia, eclampsia, or uncontrolled gestational hypertension.
• Placental abnormality.
• Polyhydramnios or oligohydramnios.
• Significant bleeding or blood clotting disorder.
• 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.
• 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.
• Antituberculosis treatment use currently or at any time during this current pregnancy.

Key Exclusion Criteria - Infant Participants

• 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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo	Biological: Placebp; Placebo
Experimental: RSVpreF vaccine; RSV vaccine (RSVpreF)	Biological: RSVpreF vaccine; RSVpreF vaccine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Maternal Participants With Prespecified Local Reactions Within 7 Days After Vaccination	Local reactions included redness, swelling, and pain at injection site and were recorded in electronic diary (e-diary). Redness and swelling were measured by the maternal participant and recorded in measuring device units (mdu) in the e-diary (range: 1 to 21). 1 mdu = 0.5 centimetre (cm). Redness and swelling were graded as mild (>2.0 to 5.0 cm), moderate (>5.0 to 10.0 cm), severe (>10.0 cm) and grade 4 (necrosis or exfoliative dermatitis for redness and necrosis for swelling). Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), severe (prevented daily activity) and grade 4 (emergency room visit or hospitalization for severe pain at the injection site). Grade 4 reactions were classified by the investigator or medically qualified designee.	From Day 1 to Day 7 after vaccination
Percentage of Maternal Participants With Prespecified Systemic Events Within 7 Days After Vaccination	Systemic events included fever, fatigue, headache, nausea, muscle pain, joint pain, vomiting and diarrhea and were recorded by participants in the e-diary. Fever was defined as an oral temperature greater than or equal to (>=) 38.0 degree Celsius (C) and classified as mild (38.0 to 38.4 degree C), moderate (38.5 to 38.9 degree C), severe (39.0 to 40.0 degree C) and grade 4 (>40.0 degree C). Headache, nausea, fatigue, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity), severe (prevented daily activity). Vomiting: mild (1-2 times in 24 hours [H]), moderate (>2 times in 24 H), severe (required intravenous [IV] hydration). Diarrhea: mild (2-3 loose stools in 24 H), moderate (4-5 loose stools in 24 H), severe (>=6 loose stools in 24 H). For all systemic events except fever, Grade 4= emergency room visit or hospitalization. Grade 4 events were classified by investigator or medically qualified designee.	From Day 1 to Day 7 after vaccination
Percentage of Maternal Participants With Adverse Events (AEs) From the Time of Vaccination Through 1 Month After Vaccination	An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Only AEs collected by non-systematic assessment (i.e. excluding local reactions and systemic events) were included in this outcome measure.	From vaccination on Day 1 up to 1 month after vaccination
Percentage of Maternal Participants With Adverse Event of Special Interest (AESIs)	AESIs are a subset of targeted medical events based on review of known pharmacology, toxicology findings, possible class effects, published literature, and signals arising from safety data assessments, and on population under study. AESIs were based on targeted medical events associated with pregnant maternal participants prior to/during delivery and post delivery. For maternal participants, the following were considered as protocol defined AESIs: diagnosis of Guillain-Barré syndrome; diagnosis of acute polyneuropathy without an underlying etiology; hypertensive disorders of pregnancy; preterm delivery (delivery at <37 0/7 weeks' gestation) and atrial fibrillation. AESIs was to be recorded as an AE or serious adverse event (SAE) on the case report form (CRF).	From vaccination on Day 1 up to 6 months after delivery (up to maximum of 10 months)
Percentage of Maternal Participants With SAEs From Vaccination Throughout the Study	An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event.	From vaccination on Day 1 up to 6 months after delivery (up to maximum of 10 months)
Percentage of Infant Participants With AESIs From Birth Through 6 Months of Age	AESIs are a subset of targeted medical events based on review of known pharmacology, toxicology findings, possible class effects, published literature, and signals arising from safety data assessments, and on population under study. AESIs were based on targeted medical events associated with infants at birth. For infant participants the following were considered as protocol defined AESIs: preterm birth (born at <37 0/7 week's gestation); birth weight 1001-2500 grams (g); developmental delay. Extremely preterm birth (born at <28 0/7 week's gestation) and extremely low birth weight (less than or equal to [<=] 1000 g) were reported as serious AESIs.	From birth up to 6 months of age
Number of Infant Participants With Reported Neonatal Deaths From Birth Through 1 Months of Age	Neonatal death was defined as the death of a live-born infant that occurred within a month after birth.	Within 1 Month after birth
Number of Infant Participants With Congenital Malformations/Anomalies at Birth	Congenital malformations/anomalies were defined as structural or functional anomalies that occurred during intrauterine life and could be identified prenatally, at birth or later in life.	At birth
Number of Infant Participants With Other Neonatal Problems at Birth	Other neonatal problem included dysmaturity, neonatal illness, hospitalization, and drug therapies.	At birth
Number of Infant Participants According to Appearance, Pulse, Grimace, Activity, and Respiration (APGAR) Score at 1 Minute After Birth	APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to <7 was moderate, and <4 was poor.	1 minute after birth
Number of Infant Participants According to APGAR Score at 5 Minutes After Birth	APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to <7 was moderate, and <4 was poor.	5 minutes after birth
Number of Infant Participants According to APGAR Score at 10 Minutes After Birth	APGAR was a fast evaluation technique used to evaluate a newborn baby's overall health. APGAR stands for (A) Appearance (skin coloration), (P) Pulse (heart rate), (G) Grimace (reflex response), (A) Activity (muscle tone) and (R) Respiration (breathing). Each component was given a score of 0, 1, or 2; after summing up scores for each component a total possible score was of 0 (worst condition) to 10 (best condition), where higher scores indicate better health. A score of 7 to 10 was good, 4 to <7 was moderate, and <4 was poor.	10 minutes after birth
Number of Infant Participants According to Gestational Age (GA) at Birth	GA at birth was collected as:>=24 to <28 weeks, >=28 to <34 weeks, >=34 to <37 weeks, >=37 to <42 weeks, and >=42 weeks.	At birth
Number of Infant Participants Requiring Hospitalization at Birth	Length of hospitalization at birth refers to the amount of time the infant remains admitted to the healthcare facility immediately following delivery and if that length of time is greater than or less than 72 hours. Postnatal standard of care procedures in South Africa were as follows: healthy newborns and their mothers were typically discharged within 24 hours after an uncomplicated vaginal delivery, or within 72 hours following an uncomplicated Caesarean section. These practices were supported by the Guidelines for Maternity Care in South Africa.	From birth until discharge from hospitalization (up to a maximum of 72 hours)
Percentage of Infant Participants With AEs From Birth to 1 Month of Age	An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention.	From birth to 1 month of age
Percentage of Infant Participants With SAEs From Birth Through 6 Months of Age	An AE was any untoward medical occurrence in a participant or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An SAE was any untoward medical occurrence that at any dose: resulted in death, was life threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect or that was considered an important medical event.	From birth to 6 months of age
Percentage of Infant Participants With Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Birth Through 6 Months of Age	An NDCMC was defined as a disease or medical condition, not previously identified, that was expected to be persistent or otherwise long-lasting in its effects. NDCMCs were reported as both AEs and SAEs.	From birth to 6 months of age

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Geometric Mean Titer (GMT) of Neutralizing Titer (NTs) for Respiratory Syncytial Virus Subgroup A (RSV A) and Respiratory Syncytial Virus Subgroup B (RSV B) Before Vaccination and at Delivery: Maternal Participants	GMTs and the corresponding 2-sided 95% confidence intervals (CIs) were calculated by exponentiating the mean logarithm of the neutralizing titers and the corresponding CIs based on the Student t distribution.	Before vaccination on Day 1 and at delivery
Geometric Mean Fold Rise (GMFR) of NTs for RSV A and RSV B From Before Vaccination to Delivery: Maternal Participants	GMFRs and the corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the fold rises and the corresponding CIs based on the Student t distribution. The GMFR for each vaccine group was defined as the geometric mean of the fold rises in the assay results from the specified time points.	Before vaccination on Day 1 to delivery

Collaborators and Investigators

• Sponsor: Pfizer
• Investigators: Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

General Publications

• Myer L, Wasserman E, Tabasum S, Shittu E, Liu Y, Jose L, Horne E, Moraba RS, Wilhase A, Zar HJ, Hussen N, Mogashoa MS, Malahleha M, Madhi SA, Sarwar UN, Snaggs H, Erdem R, Radley D, Kalinina EV, Pahud BA, Maddalena Lino M, Anastasiou OE, Swanson KA, Anderson AS, Gurtman A, Munjal I. Safety, Tolerability, and Immunogenicity of RSVpreF Vaccine in Pregnant Individuals Living with HIV. Vaccines (Basel). 2025 Dec 1;13(12):1218. doi: 10.3390/vaccines13121218.

Helpful Links

• To obtain contact information for a study center near you, click here.

Study record dates

Study Major Dates

• Study Start (Actual): March 12, 2024
• Primary Completion (Actual): June 11, 2025
• Study Completion (Actual): June 11, 2025

Study Registration Dates

• First Submitted: March 8, 2024
• First Submitted That Met QC Criteria: March 19, 2024
• First Posted (Actual): March 22, 2024

Study Record Updates

• Last Update Posted (Actual): July 2, 2026
• Last Update Submitted That Met QC Criteria: June 30, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: HIV; Vaccine; Maternal; Respiratory Tract Infection
• Additional Relevant MeSH Terms: Infections; Respiratory Tract Diseases; Respiratory Tract Infections
• Other Study ID Numbers: C3671032

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No