Trial Outcomes & Findings for A Study on the Safety and Immune Response to an Unadjuvanted RSV Maternal Vaccine, in High Risk Pregnant Women Aged 15 to 49 Years and Infants Born to the Vaccinated Mothers (NCT NCT04980391)

Last Updated: 2025-04-20

Results Overview

Assessed solicited administration site events included erythema, pain and swelling. Any pain = occurrence of the symptom regardless of intensity grade. Any erythema and swelling = symptom reported with a surface diameter greater than or equal to 20 millimeters.

Recruitment status

TERMINATED

Study phase

PHASE3

Target enrollment

384 participants

Primary outcome timeframe

From Day 1 to Day 7 included

Results posted on

2025-04-20

Participant Flow

Out of 384 participants who completed the informed consent process, 169 maternal participants were vaccinated, and 198 infants, including twins, were born to those exposed mothers (RSV\_MAT Group-Mother and Control Group-Mother). Therefore, 367 participants were considered exposed.

Participant milestones

Participant milestones
Measure	RSV_MAT Group-Mother Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	RSV_MAT Group-Infant This group consisted of infants born to mothers (from RSV\_MAT Group-Mother) who received a single dose of RSV MAT vaccine during pregnancy.	Control Group-Infant This group consisted of infants born to mothers (from Control Group-Mother) who received a single dose of placebo during pregnancy.
Overall Study STARTED	113	56	132	66
Overall Study COMPLETED	107	52	124	61
Overall Study NOT COMPLETED	6	4	8	5

Reasons for withdrawal

Reasons for withdrawal
Measure	RSV_MAT Group-Mother Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	RSV_MAT Group-Infant This group consisted of infants born to mothers (from RSV\_MAT Group-Mother) who received a single dose of RSV MAT vaccine during pregnancy.	Control Group-Infant This group consisted of infants born to mothers (from Control Group-Mother) who received a single dose of placebo during pregnancy.
Overall Study Death	0	0	1	1
Overall Study Lost to Follow-up	3	3	2	3
Overall Study WITHDRAWAL BY SUBJECT, NOT DUE TO AN ADVERSE EVENT	2	0	0	0
Overall Study MIGRATED / MOVED FROM THE STUDY AREA	1	1	2	1
Overall Study WITHDRAWAL BY SUBJECT'S PARENT(S)/LAR(S)	0	0	3	0

Baseline Characteristics

A Study on the Safety and Immune Response to an Unadjuvanted RSV Maternal Vaccine, in High Risk Pregnant Women Aged 15 to 49 Years and Infants Born to the Vaccinated Mothers

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	RSV_MAT Group-Infant n=132 Participants This group consisted of infants born to mothers (from RSV\_MAT Group-Mother) who received a single dose of RSV MAT vaccine during pregnancy.	Control Group-Infant n=66 Participants This group consisted of infants born to mothers (from Control Group-Mother) who received a single dose of placebo during pregnancy.	Total n=367 Participants Total of all reporting groups
Age, Customized 0 to 1 years of age	0 Participants n=93 Participants	0 Participants n=4 Participants	132 Participants n=27 Participants	66 Participants n=483 Participants	198 Participants n=36 Participants
Age, Customized 15 < 18 years of age	13 Participants n=93 Participants	6 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants	19 Participants n=36 Participants
Age, Customized 18 to 49 years of age	100 Participants n=93 Participants	50 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants	150 Participants n=36 Participants
Sex: Female, Male Female	113 Participants n=93 Participants	56 Participants n=4 Participants	63 Participants n=27 Participants	29 Participants n=483 Participants	261 Participants n=36 Participants
Sex: Female, Male Male	0 Participants n=93 Participants	0 Participants n=4 Participants	69 Participants n=27 Participants	37 Participants n=483 Participants	106 Participants n=36 Participants
Race/Ethnicity, Customized Asian	4 Participants n=93 Participants	1 Participants n=4 Participants	4 Participants n=27 Participants	1 Participants n=483 Participants	10 Participants n=36 Participants
Race/Ethnicity, Customized Black or African American	33 Participants n=93 Participants	18 Participants n=4 Participants	33 Participants n=27 Participants	18 Participants n=483 Participants	102 Participants n=36 Participants
Race/Ethnicity, Customized White	52 Participants n=93 Participants	24 Participants n=4 Participants	67 Participants n=27 Participants	34 Participants n=483 Participants	177 Participants n=36 Participants
Race/Ethnicity, Customized Other, unspecified	24 Participants n=93 Participants	13 Participants n=4 Participants	28 Participants n=27 Participants	13 Participants n=483 Participants	78 Participants n=36 Participants

PRIMARY outcome

Timeframe: From Day 1 to Day 7 included

Population: Analysis was performed on the Solicited Safety Set, which included all maternal participants who received 1 dose of a study intervention and who had solicited safety data available during the specified period.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=54 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Any Solicited Administration Site Events Any Erythema	0.9 Percentage of participants Interval 0.0 to 4.8	0 Percentage of participants Interval 0.0 to 6.6
Percentage of Maternal Participants Reporting Any Solicited Administration Site Events Any Pain	44.2 Percentage of participants Interval 34.9 to 53.9	14.8 Percentage of participants Interval 6.6 to 27.1
Percentage of Maternal Participants Reporting Any Solicited Administration Site Events Any Swelling	0 Percentage of participants Interval 0.0 to 3.2	1.9 Percentage of participants Interval 0.0 to 9.9

PRIMARY outcome

Timeframe: From Day 1 to Day 7 included

Assessed solicited systemic events included abdominal pain, diarrhea, fatigue, headache, nausea, fever \[temperature equal to or above (\>=) 38 degrees Celsius (°C)/100.4 degrees Fahrenheit (°F), regardless of the location of measurement\] and vomiting. Any = occurrence of the adverse event regardless of intensity grade or relation to study vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=54 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Abdominal pain	20.4 Percentage of participants Interval 13.4 to 29.0	16.7 Percentage of participants Interval 7.9 to 29.3
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Diarrhea	20.4 Percentage of participants Interval 13.4 to 29.0	7.4 Percentage of participants Interval 2.1 to 17.9
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Fatigue	28.3 Percentage of participants Interval 20.2 to 37.6	27.8 Percentage of participants Interval 16.5 to 41.6
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Headache	39.8 Percentage of participants Interval 30.7 to 49.5	38.9 Percentage of participants Interval 25.9 to 53.1
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Nausea	24.8 Percentage of participants Interval 17.1 to 33.8	20.4 Percentage of participants Interval 10.6 to 33.5
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Fever	0 Percentage of participants Interval 0.0 to 3.2	0 Percentage of participants Interval 0.0 to 6.6
Percentage of Maternal Participants Reporting Any Solicited Systemic Events Any Vomiting	8.0 Percentage of participants Interval 3.7 to 14.6	20.4 Percentage of participants Interval 10.6 to 33.5

PRIMARY outcome

Timeframe: From Day 1 to Day 30 included

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

An unsolicited AE was defined as any AE reported in addition to those solicited during the clinical study. Also, any 'solicited' symptom with onset outside the specified period of follow-up for solicited symptoms was reported as an unsolicited AE. Any = occurrence of any unsolicited AE regardless of intensity grade or relation to vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Any Unsolicited Adverse Events (AEs)	34.5 Percentage of participants Interval 25.8 to 44.0	37.5 Percentage of participants Interval 24.9 to 51.5

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect in the offspring of a study participant or resulted in abnormal pregnancy outcomes or in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Any Serious Adverse Events (SAEs) From Day 1 up to 42 Days Post-delivery	29.2 Percentage of participants Interval 21.0 to 38.5	19.6 Percentage of participants Interval 10.2 to 32.4

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

A participant was considered to have withdrawn from the study if no new study procedure had been performed or no new information had been collected for her since the date of withdrawal/last contact. (S)AEs leading to study withdrawal were (S)AEs identified by the investigator to cause participant withdrawal until the resolution of the event. These participant withdrawals were considered different from participant withdrawals for other reasons.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Maternal Participants Reporting (S)AEs Leading to Study Withdrawal From Day 1 up to 42 Days Post-delivery	0 Participants	0 Participants

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

An MAE was defined as an unsolicited AE for which the participant received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Medically Attended Adverse Events (MAEs) From Day 1 up to 42 Days Post-delivery	57.5 Percentage of participants Interval 47.9 to 66.8	58.9 Percentage of participants Interval 45.0 to 71.9

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Infant, which included infants live-born to exposed maternal participants, whose parents/legally acceptable representatives (LARs) completed the informed consent process and signed the informed consent form.

The percentage of live births with no congenital anomalies, live births with minor congenital anomaly(ies) only and live births with at least 1 major congenital anomaly is reported.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Live Births With no Congenital Anomalies, Live Births With Minor Congenital Anomaly(Ies) and Live Births With at Least 1 Major Congenital Anomaly LIVE BIRTH WITH NO CONGENITAL ANOMALIES	86.4 Percentage of live births Interval 79.3 to 91.7	84.8 Percentage of live births Interval 73.9 to 92.5
Percentage of Live Births With no Congenital Anomalies, Live Births With Minor Congenital Anomaly(Ies) and Live Births With at Least 1 Major Congenital Anomaly LIVE BIRTH WITH ONLY MINOR CONGENITAL ANOMALY(IES)	10.6 Percentage of live births Interval 5.9 to 17.2	13.6 Percentage of live births Interval 6.4 to 24.3
Percentage of Live Births With no Congenital Anomalies, Live Births With Minor Congenital Anomaly(Ies) and Live Births With at Least 1 Major Congenital Anomaly LIVE BIRTH WITH AT LEAST ONE MAJOR CONGENITAL ANOMALY	3.0 Percentage of live births Interval 0.8 to 7.6	1.5 Percentage of live births Interval 0.0 to 8.2

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

Pregnancy-related AESIs included preterm labor, provider-initiated preterm birth, premature preterm rupture of membranes, pre-eclampsia, pre-eclampsia with severe features including eclampsia, gestational hypertension and fetal growth restriction.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Provider-initiated preterm birth	3.5 Percentage of participants Interval 1.0 to 8.8	5.4 Percentage of participants Interval 1.1 to 14.9
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Premature preterm rupture of membranes	1.8 Percentage of participants Interval 0.2 to 6.2	5.4 Percentage of participants Interval 1.1 to 14.9
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Pre-eclampsia	4.4 Percentage of participants Interval 1.5 to 10.0	3.6 Percentage of participants Interval 0.4 to 12.3
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Pre-eclampsia with severe features including eclampsia	4.4 Percentage of participants Interval 1.5 to 10.0	0 Percentage of participants Interval 0.0 to 6.4
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Gestational hypertension	0.9 Percentage of participants Interval 0.0 to 4.8	3.6 Percentage of participants Interval 0.4 to 12.3
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Fetal growth restriction	1.8 Percentage of participants Interval 0.2 to 6.2	3.6 Percentage of participants Interval 0.4 to 12.3
Percentage of Maternal Participants Reporting Pregnancy-related Adverse Events of Special Interest (AESIs) From Day 1 up to 42 Days Post-delivery Preterm labor	8.0 Percentage of participants Interval 3.7 to 14.6	7.1 Percentage of participants Interval 2.0 to 17.3

PRIMARY outcome

Timeframe: From Day 1 up to 42 days post-delivery, an average of 2 months

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

Worsening of pre-existing medical condition and/or obstetric complication was considered by the investigator, using clinical judgment and the following criteria: * Change in medication and/or medication dose. * Medically attended event in relation to pre-existing condition and/or obstetric complication that are outside the routine management of the condition/complication. * SAE and/or hospitalization in relation to pre-existing condition and/or obstetric complication.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 42 Days Post-delivery Change In Medication And/Or Medication Dose	1.8 Percentage of participants Interval 0.2 to 6.2	1.8 Percentage of participants Interval 0.0 to 9.6
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 42 Days Post-delivery Medically Attended Event In Relation To Pre-Existing Condition And/Or Obstetric Complication	1.8 Percentage of participants Interval 0.2 to 6.2	7.1 Percentage of participants Interval 2.0 to 17.3
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 42 Days Post-delivery SAE And/Or Hospitalization In Relation To Pre-Existing Condition And/Or Obstetric Complication	1.8 Percentage of participants Interval 0.2 to 6.2	3.6 Percentage of participants Interval 0.4 to 12.3

PRIMARY outcome

Timeframe: From birth up to 42 days post-birth, an average of 2 months

Population: Analysis was performed on the Exposed Set - Infant, which included infants live-born to exposed maternal participants, whose parents/LARs completed the informed consent process and signed the informed consent form.

Neonatal/infant AESIs included low birth weight (below \[\<\] 2500 grams), very low birth weight (\<1500 grams), extremely low birth weight (\<1000 grams), preterm birth (\<37 weeks of gestational age), small for gestational age (weight below 10th percentile for gestational age), congenital anomalies with internal structural defects and neonatal death in a preterm live birth (gestational age equal to or above \[\>=\] 28 and \<37 weeks).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Low Birth Weight (<2500 grams)	16.7 Percentage of participants Interval 10.7 to 24.1	18.2 Percentage of participants Interval 9.8 to 29.6
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Very Low Birth Weight (<1500 grams)	2.3 Percentage of participants Interval 0.5 to 6.5	1.5 Percentage of participants Interval 0.0 to 8.2
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Extremely Low Birth Weight (<1000 grams)	0 Percentage of participants Interval 0.0 to 2.8	1.5 Percentage of participants Interval 0.0 to 8.2
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Preterm Birth (<37 Weeks Of Gestational Age)	18.2 Percentage of participants Interval 12.0 to 25.8	19.7 Percentage of participants Interval 10.9 to 31.3
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Small For Gestational Age	14.4 Percentage of participants Interval 8.9 to 21.6	27.3 Percentage of participants Interval 17.0 to 39.6
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Congenital Anomalies With Internal Structural Defects	3.0 Percentage of participants Interval 0.8 to 7.6	0 Percentage of participants Interval 0.0 to 5.4
Percentage of Infant Participants Reporting Neonatal/Infant AESIs From Birth up to 42 Days Post-birth Neonatal Death In A Preterm Live Birth (gestational age >=28 and <37 weeks)	0.8 Percentage of participants Interval 0.0 to 4.1	1.5 Percentage of participants Interval 0.0 to 8.2

PRIMARY outcome

Timeframe: From birth up to 42 days post-birth, an average of 2 months

An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Any SAEs From Birth up to 42 Days Post-birth	20.5 Percentage of participants Interval 13.9 to 28.3	27.3 Percentage of participants Interval 17.0 to 39.6

PRIMARY outcome

Timeframe: From birth up to 42 days post-birth, an average of 2 months

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 42 Days Post-birth	0 Participants	0 Participants

PRIMARY outcome

Timeframe: From birth up to 42 days post-birth, an average of 2 months

An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting MAEs From Birth up to 42 Days Post-birth	56.8 Percentage of participants Interval 47.9 to 65.4	54.5 Percentage of participants Interval 41.8 to 66.9

PRIMARY outcome

Timeframe: From birth up to 180 days post-birth

An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Any SAEs From Birth up to 180 Days Post-birth	25.0 Percentage of participants Interval 17.9 to 33.3	30.3 Percentage of participants Interval 19.6 to 42.9

PRIMARY outcome

Timeframe: From birth up to 180 days post-birth

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 180 Days Post-birth	0 Participants	0 Participants

PRIMARY outcome

Timeframe: From birth up to 180 days post-birth

An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting MAEs From Birth up to 180 Days Post-birth	77.3 Percentage of participants Interval 69.2 to 84.1	69.7 Percentage of participants Interval 57.1 to 80.4

PRIMARY outcome

Timeframe: From birth up to 365 days post-birth

An SAE was defined as any untoward medical occurrence that resulted in death, was life-threatening, required hospitalization or prolongation of existing hospitalization, resulted in disability/incapacity, was a congenital anomaly/birth defect or resulted in other situations that were considered serious per medical or scientific judgment. Any = occurrence of any SAE regardless of intensity grade or relation to vaccination.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Any SAEs From Birth up to 365 Days Post-birth	26.5 Percentage of participants Interval 19.2 to 34.9	31.8 Percentage of participants Interval 20.9 to 44.4

PRIMARY outcome

Timeframe: From birth up to 365 days post-birth

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Infant Participants Reporting (S)AEs Leading to Study Withdrawal From Birth up to 365 Days Post-birth	0 Participants	0 Participants

PRIMARY outcome

Timeframe: From birth up to 365 days post-birth

An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting MAEs From Birth up to 365 Days Post-birth	86.4 Percentage of participants Interval 79.3 to 91.7	75.8 Percentage of participants Interval 63.6 to 85.5

PRIMARY outcome

Timeframe: At pre-dosing (Day 1)

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time point (i.e. pre-dosing \[Day 1\]), minus those participants with protocol deviations that lead to exclusion.

RSV MAT IgG-specific antibody concentrations were determined by enzyme-linked immunosorbent assay (ELISA) and expressed as geometric mean concentrations (GMCs) in ELISA units per milliliter (ELU/mL).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=103 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=48 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT Immunoglobulin G (IgG)-Specific Antibody Concentrations for Maternal Participants at Pre-dosing (Day 1)	4981.6 ELU/mL Interval 4405.14 to 5633.53	5981.7 ELU/mL Interval 4908.71 to 7289.11

PRIMARY outcome

Timeframe: At delivery

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time point (i.e. delivery), minus those participants with protocol deviations that lead to exclusion.

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=99 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=44 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Maternal Participants at Delivery	70337.1 ELU/mL Interval 60711.34 to 81489.07	4421 ELU/mL Interval 3477.9 to 5619.8

PRIMARY outcome

Timeframe: At pre-dosing (Day 1)

RSV-A neutralizing titers were determined by neutralization assay and expressed as geometric mean titers (GMTs).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=103 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=48 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1)	681.5 Titers Interval 578.33 to 803.11	752.4 Titers Interval 580.25 to 975.5

PRIMARY outcome

Timeframe: At delivery

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time point (i.e. delivery), minus those participants with protocol deviations that lead to exclusion.

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=99 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=44 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Maternal Participants at Delivery	6240.3 Titers Interval 5026.02 to 7747.88	612.8 Titers Interval 455.82 to 823.83

PRIMARY outcome

Timeframe: At delivery (for maternal participants) or within 72 hours after birth (for infant participants)

Population: Analysis was performed on all pairs of maternal participants (from Per Protocol Set Immunogenicity - Maternal) and their infants (from Per Protocol Set Immunogenicity - Infant) with available results for this outcome measure at the specified time points.

The placental transfer ratio of IgG-specific antibody concentration was determined from cord blood (or infant blood sample collected within 72 hours after birth \[if no cord blood could be obtained\]) over that of the blood sample from mother at delivery (if no blood sample was collected during delivery).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=86 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=37 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Geometric Mean Ratio (GMR) Between Cord Blood and Maternal RSV MAT IgG-specific Antibody Concentrations	1.33 Ratio Interval 1.04 to 1.7	2.30 Ratio Interval 1.63 to 3.25

PRIMARY outcome

Timeframe: At delivery or within 72 hours after birth

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Infant, which included all infant participants in the Exposed set who had post-delivery/birth immunogenicity data available for the specified analysis at the specified time points, minus those who (a) were born less than 4 weeks post-maternal participant dosing and/ or (b) had protocol deviations that lead to exclusion.

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL. The antibody concentrations were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=88 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=37 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Delivery or Within 72 Hours After Birth	77625.1 ELU/mL Interval 63706.97 to 94583.89	9228 ELU/mL Interval 6540.47 to 13019.71

PRIMARY outcome

Timeframe: At delivery or within 72 hours after birth

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs. The titers were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=91 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=37 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Infant Participants at Delivery or Within 72 Hours After Birth	9080.2 Titers Interval 7449.56 to 11067.75	694.6 Titers Interval 495.72 to 973.37

SECONDARY outcome

Timeframe: From Day 1 up to 180 days post-delivery

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Any SAEs From Day 1 up to 180 Days Post-delivery	29.2 Percentage of participants Interval 21.0 to 38.5	19.6 Percentage of participants Interval 10.2 to 32.4

SECONDARY outcome

Timeframe: From Day 1 up to 180 days post-delivery

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Maternal Participants Reporting (S)AEs Leading to Study Withdrawal From Day 1 up to 180 Days Post-delivery	0 Participants	0 Participants

SECONDARY outcome

Timeframe: From Day 1 up to 180 days post-delivery

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

An MAE was defined as an unsolicited AE for which the participants received medical attention such as hospitalization, or an emergency room visit, or visit to/by a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting MAEs From Day 1 up to 180 Days Post-delivery	61.1 Percentage of participants Interval 51.4 to 70.1	60.7 Percentage of participants Interval 46.8 to 73.5

SECONDARY outcome

Timeframe: From Day 1 up to 180 days post-delivery

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

Worsening of pre-existing medical condition and/or obstetric complication was considered by the investigator, using clinical judgement and the following criteria: * Change in medication and/or medication dose. * Medically attended event in relation to pre-existing condition and/or obstetric complication that are outside the routine management of the condition/complication. * SAE and/or hospitalization in relation to pre-existing condition and/or obstetric complication.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 180 Days Post-delivery Change In Medication And/Or Medication Dose	1.8 Percentage of participants Interval 0.2 to 6.2	1.8 Percentage of participants Interval 0.0 to 9.6
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 180 Days Post-delivery Medically Attended Event In Relation To Pre-Existing Condition And/Or Obstetric Complication	1.8 Percentage of participants Interval 0.2 to 6.2	7.1 Percentage of participants Interval 2.0 to 17.3
Percentage of Maternal Participants Reporting Worsening of Pre-existing Medical Conditions and/or Obstetric Complications From Day 1 up to 180 Days Post-delivery SAE And/Or Hospitalization In Relation To Pre-Existing Condition And/Or Obstetric Complication	1.8 Percentage of participants Interval 0.2 to 6.2	3.6 Percentage of participants Interval 0.4 to 12.3

SECONDARY outcome

Timeframe: From Day 1 up to 180 days post-delivery

Population: Analysis was performed on the Exposed Set - Maternal, which included all maternal participants who received 1 dose of a study intervention.

RSV-associated MA-RTI was defined as a medically attended visit for RTI symptoms and confirmed RSV infection.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=113 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=56 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Number of Maternal Participants Reporting RSV-associated Medically Attended Respiratory Tract Illnesses (MA-RTIs) From Day 1 up to 180 Days Post-delivery	0 Participants	0 Participants

SECONDARY outcome

Timeframe: From birth up to 365 days post-birth

An RSV-associated LRTI is characterized by a history of cough OR difficulty in breathing, AND a blood oxygen saturation by pulse oximetry (SpO2) lower than (\<) 95%, OR respiratory rate increase AND a confirmed RSV infection. An RSV-associated severe LRTI meets the case definition of RSV-LRTI AND is additionally characterized by a SpO2 \<93%, OR lower chest wall in-drawing, OR inability to feed, OR failure to respond/unconscious.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Medically Assessed, RSV-associated Lower Respiratory Tract Illness (LRTIs) of Any Severity and RSV-associated Severe LRTIs From Birth up to 365 Days Post-birth Any RSV-associated LRTIs	0.8 Percentage of participants Interval 0.0 to 4.1	3.0 Percentage of participants Interval 0.4 to 10.5
Percentage of Infant Participants Reporting Medically Assessed, RSV-associated Lower Respiratory Tract Illness (LRTIs) of Any Severity and RSV-associated Severe LRTIs From Birth up to 365 Days Post-birth RSV-associated Severe LRTIs	0 Percentage of participants Interval 0.0 to 2.8	0 Percentage of participants Interval 0.0 to 5.4

SECONDARY outcome

Timeframe: From birth up to 365 days post-birth

RSV-associated hospitalization was defined as a confirmed RSV infection and hospitalized for acute medical condition. Hospitalization was defined as admission for observation or treatment based on the judgment of a health care provider.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=132 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=66 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
Percentage of Infant Participants Reporting Medically Assessed, RSV-associated Hospitalizations From Birth up to 365 Days Post-birth	0.8 Percentage of participants Interval 0.0 to 4.1	0 Percentage of participants Interval 0.0 to 5.4

SECONDARY outcome

Timeframe: At Day 31 post-dosing

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time point (i.e. Day 31 post-dosing), minus those participants with protocol deviations that lead to exclusion.

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=89 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=38 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Maternal Participants at Day 31 Post-dosing	113957.1 ELU/mL Interval 102340.44 to 126892.37	5510.6 ELU/mL Interval 4370.3 to 6948.51

SECONDARY outcome

Timeframe: At Day 31 post-dosing

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time point (i.e. Day 31 post-dosing), minus those participants with protocol deviations that lead to exclusion.

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=89 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=38 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Maternal Participants at Day 31 Post-dosing	9959.7 Titers Interval 8239.95 to 12038.4	575.2 Titers Interval 418.4 to 790.84

SECONDARY outcome

Timeframe: At pre-dosing (Day 1), Day 31 post-dosing and delivery

Population: Analysis was performed on the Per Protocol Set Immunogenicity - Maternal, which included all maternal participants who received 1 dose of a study intervention and had immunogenicity data available for the specified analysis at the specified time points, minus those participants with protocol deviations that lead to exclusion.

RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=103 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=47 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-B Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1), Day 31 Post-dosing and Delivery Day 1	756.6 Titers Interval 646.03 to 885.98	863.4 Titers Interval 664.87 to 1121.12
RSV-B Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1), Day 31 Post-dosing and Delivery Day 31	9928.9 Titers Interval 8331.29 to 11832.87	640.7 Titers Interval 475.93 to 862.38
RSV-B Neutralizing Titers for Maternal Participants at Pre-dosing (Day 1), Day 31 Post-dosing and Delivery Delivery	6336.9 Titers Interval 5261.95 to 7631.49	650.2 Titers Interval 492.25 to 858.82

SECONDARY outcome

Timeframe: At delivery or within 72 hours after birth

RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs. The titers were measured on the cord blood sample collected at delivery, or on a blood sample collected from the infant within 72 hours after birth (if no cord blood sample could be obtained).

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=91 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=37 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-B Neutralizing Titers for Infant Participants at Delivery or Within 72 Hours After Birth	9145.5 Titers Interval 7458.74 to 11213.76	779.7 Titers Interval 566.83 to 1072.49

SECONDARY outcome

Timeframe: At Day 43 post-birth

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=16 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=5 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 43 Post-birth	29932.5 ELU/mL Interval 22576.08 to 39686.04	1310 ELU/mL Interval 546.48 to 3140.43

SECONDARY outcome

Timeframe: At Day 121 post-birth

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=3 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 121 Post-birth	4365.1 ELU/mL Interval 12.84 to 1484365.32	446.8 ELU/mL Interval 151.14 to 1320.88

SECONDARY outcome

Timeframe: At Day 181 post-birth

Population: Analysis was performed on a sub-cohort from the Per Protocol Set Immunogenicity - Infant, which included the infant participants for whom blood samples were collected for the specified analysis at Day 181 post-birth. There was only one participant in the Control Group - Infant for whom blood sample was collected, hence the 95% confidence interval (CI) associated with geometric mean could not be calculated for single participant.

RSV MAT IgG-specific antibody concentrations were determined by ELISA and expressed as GMCs in ELU/mL.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=1 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV MAT IgG-specific Antibody Concentrations for Infant Participants at Day 181 Post-birth	2857.8 ELU/mL Interval 1836.27 to 4447.53	241 ELU/mL NA indicates that the 95% CI associated with geometric mean could not be calculated for single participant.

SECONDARY outcome

Timeframe: At Day 43 post-birth

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=17 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=5 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Infant Participants at Day 43 Post-birth	3203.8 Titers Interval 1919.77 to 5346.65	240.5 Titers Interval 53.94 to 1072.76

SECONDARY outcome

Timeframe: At Day 121 post-birth

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=3 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Infant Participants at Day 121 Post-birth	607.9 Titers Interval 0.28 to 1322707.87	94.1 Titers Interval 68.1 to 130.08

SECONDARY outcome

Timeframe: At Day 181 post-birth

RSV-A neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=1 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-A Neutralizing Titers for Infant Participants at Day 181 Post-birth	755 Titers Interval 0.45 to 1262151.64	115 Titers NA indicates that the 95% CI associated with geometric mean could not be calculated for single participant.

SECONDARY outcome

Timeframe: At Day 43 post-birth

RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=17 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=5 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-B Neutralizing Titers for Infant Participants at Day 43 Post-birth	3012.8 Titers Interval 1789.81 to 5071.6	273.3 Titers Interval 106.14 to 703.45

SECONDARY outcome

Timeframe: At Day 121 post-birth

RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=3 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-B Neutralizing Titers for Infant Participants at Day 121 Post-birth	622.7 Titers Interval 2.98 to 129923.7	54.9 Titers Interval 27.69 to 108.83

SECONDARY outcome

Timeframe: At Day 181 post-birth

RSV-B neutralizing titers were determined by neutralization assay and expressed as GMTs.

Outcome measures

Outcome measures
Measure	RSV_MAT Group-Mother n=2 Participants Maternal participants randomized to the RSV\_MAT Group received a single dose of the RSV MAT vaccine administered, between 24 and 36 weeks of gestation, at Day 1 in this study.	Control Group-Mother n=1 Participants Maternal participants randomized to the Control Group received a single dose of Placebo administered, between 24 and 36 weeks of gestation, at Day 1 in this study.
RSV-B Neutralizing Titers for Infant Participants at Day 181 Post-birth	327.9 Titers Interval 6.57 to 16367.16	63 Titers NA indicates that the 95% CI associated with geometric mean could not be calculated for single participant.

Adverse Events

RSV_MAT Group-Mother

Serious events: 33 serious events

Other events: 89 other events

Deaths: 0 deaths

Control Group-Mother

Serious events: 11 serious events

Other events: 38 other events

Deaths: 0 deaths

RSV_MAT Group-Infant

Serious events: 35 serious events

Other events: 118 other events

Deaths: 1 deaths

Control Group-Infant

Serious events: 21 serious events

Other events: 57 other events

Deaths: 1 deaths

Serious adverse events

Other adverse events

Additional Information

GSK Response Center

GlaxoSmithKline

Phone: 866-435-7343

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee GSK agreements may vary with individual investigators, but will not prohibit any investigator from publishing. GSK supports the publication of results from all centers of a multi-center trial but requests that reports based on single site data not precede the primary publication of the entire clinical trial.
Publication restrictions are in place

Restriction type: OTHER