Respiratory Syncytial VirusPhase 3MORISOTNCT06325657
A Study to Learn About the Vaccine RSVpreF In Pregnant Participants With HIV and Their Infants
A Phase 3 study testing RSVpreF vaccine and Placebp in people with Respiratory Syncytial Virus, run by Pfizer at 14 sites in South Africa.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 0 to 49 years
- Conditions the study is for
- Respiratory Syncytial Virus
- What is being tested?
- RSVpreF vaccine and Placebp
- Type of treatment
- Vaccines
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 681 participants
- Where
- 14 sitesSouth Africa
- Study dates
- 12 Mar 2024to 11 Jun 2025
- Phase
- Phase 3
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 0 to 49 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- 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.
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- 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
Who cannot join
- 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:
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- 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.
- 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.
Trial locations and contacts
14 sites in 1 country.
14 sites in 1 country
South Africa14 sites
Worthwhile Clinical Trials
Benoni, Gauteng, 1500
Josha Research
Bloemfontein, Free State, 9301
REIMED Reiger Park
Boksburg, Gauteng, 1459
MRC Unit on Child And Adolescent Health
Cape Town, Western Cape, 7700
Gugulethu Green Clinic
Cape Town, Western Cape, 7750
Synergy Biomed Research Institute
East London, Eastern Cape, 5241
Wits RHI
Johannesburg, Gauteng, 2001
University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA)
Johannesburg, Gauteng, 2013
Wits VIDA Nkanyezi Research Unit
Johannesburg, Gauteng, 2093
Qhakaza Mbokodo Research Clinic
Ladysmith, KwaZulu-Natal, 3370
Gole Biomed Research Centre
Polokwane, Limpopo, 0699
Setshaba Research Centre
Pretoria, Gauteng, 0152
Botho Ke Bontle Health Services
Pretoria, Gauteng, 0184
FAMCRU - Worcester
Worcester, Western Cape, 6850
About this study
Official title: 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.
Read more
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.
- Conditions
- Respiratory Syncytial Virus
- Being tested
- RSVpreF vaccine, Placebp
- Keywords
- Respiratory Tract Infection, HIV, Maternal, Vaccine
- Medical subject headings
- Respiratory Tract Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RSVpreF vaccineBiological
RSVpreF vaccine
PlacebpBiological
Placebo
| Study group | Role | What they receive |
|---|---|---|
| RSVpreF vaccine | Experimental | RSV vaccine (RSVpreF) Receives: Biological: RSVpreF vaccine |
| Placebo | Placebo comparator | Placebo Receives: Biological: Placebp |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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.
Measured: 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).
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: At birth
Number of Infant Participants With Other Neonatal Problems at Birth
Other neonatal problem included dysmaturity, neonatal illness, hospitalization, and drug therapies.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: From birth to 6 months of age
Secondary outcomes (2)
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.
Measured: 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.
Measured: Before vaccination on Day 1 to delivery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Mar 2024
- Study start12 Mar 2024
- Primary completion11 Jun 2025
- Study completion11 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Respiratory Syncytial VirusStudies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 681 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06325657
- Sponsor's protocol ID
- C3671032
- Acronym
- MORISOT
- Status last verified
- Jun 2026
- First submitted
- 8 Mar 2024
- Last updated
- 2 Jul 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: 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.
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.
PubMed 41441684