Trial Outcomes & Findings for A Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of Adenovirus Serotype 26 Based Respiratory Syncytial Virus Pre-fusion (Ad26.RSV.Pre-F) Vaccine in RSV-Seronegative Toddlers 12 to 24 Months of Age (NCT NCT03606512)

Last Updated: 2025-02-04

Results Overview

An AE is any untoward medical event that occurs in a participants administered an investigational product, and it does not necessarily indicate only events with a clear causal relationship with the relevant investigational product. Solicited local and systemic AEs were precisely defined events that participants were specifically asked about and which were noted by participants in the diary. Solicited local AEs included injection-site pain/tenderness, injection-site erythema and injection-site swelling/induration. Solicited systemic AEs included fatigue, headache, nausea, myalgia and fever.

Recruitment status

COMPLETED

Study phase

PHASE1/PHASE2

Target enrollment

38 participants

Primary outcome timeframe

Up to Day 8 (7 days after first vaccination on Day 1)

Results posted on

2025-02-04

Participant Flow

Participant milestones

Participant milestones
Measure	Placebo/Nimenrix Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Overall Study STARTED	18	20
Overall Study Participants Received Placebo on Day 57	6	0
Overall Study Participants Received Nimenrix on Day 57	12	0
Overall Study COMPLETED	18	18
Overall Study NOT COMPLETED	0	2

Reasons for withdrawal

Reasons for withdrawal
Measure	Placebo/Nimenrix Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Overall Study Lost to Follow-up	0	1
Overall Study 'moved from study area	0	1

Baseline Characteristics

A Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of Adenovirus Serotype 26 Based Respiratory Syncytial Virus Pre-fusion (Ad26.RSV.Pre-F) Vaccine in RSV-Seronegative Toddlers 12 to 24 Months of Age

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=20 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.	Total n=38 Participants Total of all reporting groups
Age, Continuous	18.5 months n=5 Participants	15 months n=7 Participants	16.5 months n=5 Participants
Age, Customized From 12 months to 24 months	18 Participants n=5 Participants	20 Participants n=7 Participants	38 Participants n=5 Participants
Sex: Female, Male Female	11 Participants n=5 Participants	11 Participants n=7 Participants	22 Participants n=5 Participants
Sex: Female, Male Male	7 Participants n=5 Participants	9 Participants n=7 Participants	16 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	2 Participants n=5 Participants	3 Participants n=7 Participants	5 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	16 Participants n=5 Participants	17 Participants n=7 Participants	33 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Asian	1 Participants n=5 Participants	1 Participants n=7 Participants	2 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	1 Participants n=5 Participants	2 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) White	13 Participants n=5 Participants	16 Participants n=7 Participants	29 Participants n=5 Participants
Race (NIH/OMB) More than one race	3 Participants n=5 Participants	0 Participants n=7 Participants	3 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	1 Participants n=7 Participants	1 Participants n=5 Participants
Region of Enrollment AUSTRALIA	6 Participants n=5 Participants	8 Participants n=7 Participants	14 Participants n=5 Participants
Region of Enrollment BRAZIL	2 Participants n=5 Participants	3 Participants n=7 Participants	5 Participants n=5 Participants
Region of Enrollment CANADA	3 Participants n=5 Participants	2 Participants n=7 Participants	5 Participants n=5 Participants
Region of Enrollment FINLAND	5 Participants n=5 Participants	6 Participants n=7 Participants	11 Participants n=5 Participants
Region of Enrollment POLAND	2 Participants n=5 Participants	1 Participants n=7 Participants	3 Participants n=5 Participants

PRIMARY outcome

Timeframe: Up to Day 8 (7 days after first vaccination on Day 1)

Population: The Full Analysis set (FAS) included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=20 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Solicited Local and Systemic Adverse Events (AEs) for 7 Days After First Vaccination Solicited Local AEs	2 Participants	6 Participants	—
Number of Participants With Solicited Local and Systemic Adverse Events (AEs) for 7 Days After First Vaccination Solicited Systemic AEs	11 Participants	17 Participants	—

PRIMARY outcome

Timeframe: Up to Day 36 (7 days after second vaccination on Day 29)

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=20 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Solicited Local and Systemic AEs for 7 Days After Second Vaccination Solicited Local AEs	1 Participants	9 Participants	—
Number of Participants With Solicited Local and Systemic AEs for 7 Days After Second Vaccination Solicited Systemic AEs	9 Participants	11 Participants	—

PRIMARY outcome

Timeframe: Up to Day 64 (7 days after third vaccination on Day 57)

Population: The FAS included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations. Here, 'N' (Number of participants analyzed) included number of participants evaluable for this outcome measure. Data for this outcome measure was planned to be collected and analyzed per the administered study vaccination type.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=6 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=12 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF n=19 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Solicited Local and Systemic AEs for 7 Days After Third Vaccination Solicited Local AEs	1 Participants	4 Participants	7 Participants
Number of Participants With Solicited Local and Systemic AEs for 7 Days After Third Vaccination Solicited Systemic AEs	3 Participants	4 Participants	12 Participants

PRIMARY outcome

Timeframe: Up to Day 29 (28 days after first vaccination on Day 1)

An AE is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with a clear causal relationship with the relevant investigational product. Unsolicited AEs were precisely defined events that participants were not asked about and which were not noted by participants in the diary.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=20 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Unsolicited AEs for 28 Days After First Vaccination	5 Participants	9 Participants	—

PRIMARY outcome

Timeframe: Up to Day 57 (28 days after second vaccination on Day 29)

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=20 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Unsolicited AEs for 28 Days After Second Vaccination	7 Participants	9 Participants	—

PRIMARY outcome

Timeframe: Up to Day 85 (28 days after third vaccination on Day 57)

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=19 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=6 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF n=12 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Unsolicited AEs for 28 Days After Third Vaccination	7 Participants	3 Participants	3 Participants

PRIMARY outcome

Timeframe: Up to 2 year 10 months

Population: The FAS included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations. Data for this outcome measure was planned to be collected and analyzed per the administered study vaccination type.

Number of participants with SAEs were reported. An AE is any untoward medical event that occurs in a participants administered an investigational product, and it does not necessarily indicate only events with a clear causal relationship with the relevant investigational product. SAE is any AE that results in: death, persistent or significant disability/incapacity, requires inpatient hospitalization or prolongation of existing hospitalization, is life-threatening experience, is a suspected transmission of any infectious agent via a medicinal product, is a congenital anomaly/birth defect and may jeopardize participant and/or may require medical or surgical intervention to prevent one of the outcomes listed above.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=20 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=6 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF n=12 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Serious Adverse Events (SAEs)	1 Participants	0 Participants	0 Participants

SECONDARY outcome

Timeframe: Days 1, 8, 85, and 267 (End of first RSV season)

Population: The Per-protocol Immunogenicity (PPI) analysis set included all randomized and vaccinated participants for whom immunogenicity data are available, excluding participants with major protocol deviations expecting to impact the immunogenicity outcomes. Here, 'n' (number analyzed) included number of participants evaluable for specified time points. Here, values below the seropositivity cut-off (less than \[\<\] 42.7) were imputed with zero.

Neutralizing antibody titers assessed by virus neutralizing antibodies (VNA) against the RSV A2 strain were expressed as 50% inhibitory concentration (IC50) units.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=19 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Titers of Neutralizing Antibodies to Respiratory Syncytial Virus (RSV) A2 Strain Day 8	NA Titers Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 42.7.	NA Titers Interval to 52.0 Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 42.7.	—
Titers of Neutralizing Antibodies to Respiratory Syncytial Virus (RSV) A2 Strain Day 1	NA Titers Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below lower limit of quantification (LLOQ) of 42.7.	NA Titers Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 42.7.	—
Titers of Neutralizing Antibodies to Respiratory Syncytial Virus (RSV) A2 Strain Day 85	NA Titers Interval to 45.0 Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 42.7.	293 Titers Interval 240.0 to 358.0	—
Titers of Neutralizing Antibodies to Respiratory Syncytial Virus (RSV) A2 Strain Day 267 (End of first RSV season)	NA Titers Interval to 46.0 Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 42.7.	269 Titers Interval 115.0 to 632.0	—

SECONDARY outcome

Timeframe: Days 1, 8, 85, and 267 (End of first RSV season)

Population: The PPI analysis set included all randomized and vaccinated participants for whom immunogenicity data are available, excluding participants with major protocol deviations expecting to impact the immunogenicity outcomes. Here, 'n' (number analyzed) included number of participants evaluable for specified time points.

Pre-fusion A IgG serum antibody response was assessed by ELISA.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=19 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Pre-Fusion A Immunoglobulin G (IgG) Serum Antibody Response as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) Day 1	NA ELISA units per liter (EU/L) Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	NA ELISA units per liter (EU/L) Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	—
Pre-Fusion A Immunoglobulin G (IgG) Serum Antibody Response as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) Day 8	NA ELISA units per liter (EU/L) Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	NA ELISA units per liter (EU/L) Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	—
Pre-Fusion A Immunoglobulin G (IgG) Serum Antibody Response as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) Day 85	NA ELISA units per liter (EU/L) Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	236 ELISA units per liter (EU/L) Interval 187.0 to 299.0	—
Pre-Fusion A Immunoglobulin G (IgG) Serum Antibody Response as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) Day 267 (End of first RSV season)	NA ELISA units per liter (EU/L) Interval to 27.0 Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 16.1.	212 ELISA units per liter (EU/L) Interval 79.0 to 571.0	—

SECONDARY outcome

Timeframe: Days 1, 8, 85, and 267 (End of first RSV season)

Population: The PPI analysis set included all randomized and vaccinated participants for whom immunogenicity data are available, excluding participants with major protocol deviations expecting to impact the immunogenicity outcomes. Here, 'n' (number analyzed) is number of participants evaluable for specified time points.

Post-fusion A IgG serum antibody response as assessed by ELISA was reported.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=19 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Post-Fusion A IgG Serum Antibody Response as Assessed by ELISA Day 1	NA EU/L Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	NA EU/L Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	—
Post-Fusion A IgG Serum Antibody Response as Assessed by ELISA Day 8	NA EU/L Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	NA EU/L Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	—
Post-Fusion A IgG Serum Antibody Response as Assessed by ELISA Day 85	NA EU/L Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	47 EU/L Interval 40.0 to 54.0	—
Post-Fusion A IgG Serum Antibody Response as Assessed by ELISA Day 267 (End of first RSV season)	NA EU/L Interval to 30.0 Here, NA signifies that Geometric mean and 95% CI were not estimable due to being below LLOQ of 17.0.	58 EU/L Interval 22.0 to 153.0	—

SECONDARY outcome

Timeframe: Baseline (Day 1) and Day 85

Population: Data for this outcome measure was not collected due to low number of viable peripheral blood mononuclear cells (PBMC), the positive control in the intracellular cytokine staining (ICS) assay (Staphylococcal enterotoxin B \[SEB\]) could not be performed.

T-cell response (%) to RSV F peptides for T-helper Th1 and Th2 subtyping as measured by flow cytometry was planned to be assessed. Th1(% of Clusters of differentiation 4 \[CD4\]+ interferon gamma \[IFN-g\]+T cells; lower limit(s) of quantification \[LLOQ\]=0.05%) and Th2 (% of CD4+ interleukin \[IL\]-4+/IL-13+ and CD40L+T cells; LLOQ=0.07%) responses were determined by intracellular cytokines after RSV F peptide stimulation.

Outcome measures

Outcome data not reported

SECONDARY outcome

Timeframe: Up to 2 year 10 months

Population: The Modified Intent-to-treat (mITT) analysis set included participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations and who seronegative at screening but for whom there is an anamnestic response at Day 8.

Number of participants with severe RSV-LRTI were reported.

Outcome measures

Outcome measures
Measure	Placebo/Nimenrix n=18 Participants Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 months to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57. For participants in whose countries the commercial vaccine Nimenrix was licensed, placebo was replaced with Nimenrix as IM injection on Day 57 in accordance with local label and local regulations and based on joint parent/legal guardian and principal investigator (PI) decision.	Ad26.RSV.preF n=19 Participants RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 milliliters \[mL\] of 2.5\*10\^10 viral particles \[ vp\]) as an IM injection on Days 1, 29, and 57.	Ad26.RSV.preF RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Number of Participants With Severe RSV-lower Respiratory Tract Infection (LRTI)	0 Participants	0 Participants	—

Adverse Events

Placebo

Serious events: 0 serious events

Other events: 6 other events

Deaths: 0 deaths

Nimenrix

Serious events: 0 serious events

Other events: 8 other events

Deaths: 0 deaths

Ad26.RSV.preF

Serious events: 1 serious events

Other events: 15 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Placebo n=6 participants at risk Respiratory syncytial virus (RSV) seronegative toddler participants aged greater than or equal to (\>=) 12 years to less than or equal to (\<=) 24 months received placebo (matching to Ad26.RSV.preF) as an intramuscular (IM) injection on Days 1, 29 and 57.	Nimenrix n=12 participants at risk Participants received Nimenrix as an IM injection on Day 57 based on joint parent/legal guardian and PI decision, in countries where the commercial vaccine Nimenrix was licensed.	Ad26.RSV.preF n=20 participants at risk RSV seronegative toddler participants aged \>=12 months to \<=24 months received Ad26.RSV.preF (0.25 mL of 2.5\*10\^10 viral particles \[vp\]) as an IM injection on Days 1, 29, and 57.
Respiratory, thoracic and mediastinal disorders Sleep Apnoea Syndrome	0.00% 0/6 • Up to 2 year 10 months The Full Analysis set (FAS) included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations. As planned, safety data was summarized per vaccine regimen. Data for adverse events was planned to be collected and analyzed per the administered study vaccination type.	0.00% 0/12 • Up to 2 year 10 months The Full Analysis set (FAS) included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations. As planned, safety data was summarized per vaccine regimen. Data for adverse events was planned to be collected and analyzed per the administered study vaccination type.	5.0% 1/20 • Up to 2 year 10 months The Full Analysis set (FAS) included all participants who were randomized and received at least one dose of study vaccine (placebo or nimenrix, and Ad26.RSV.preF), regardless of the occurrence of protocol deviations. As planned, safety data was summarized per vaccine regimen. Data for adverse events was planned to be collected and analyzed per the administered study vaccination type.

Other adverse events

Additional Information

Clinical Franchise Leader

Janssen Vaccines & Prevention B.V

Phone: 844-434-4210

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee If an investigator wishes to publish information from the study, a copy of the manuscript must be provided to the sponsor for review at least 60 days before submission for publication or presentation. If requested by the sponsor in writing, the investigator will withhold such publication for up to an additional 60 days.
Publication restrictions are in place

Restriction type: OTHER