Trial Outcomes & Findings for A Study to Evaluate the Safety, Tolerability and Immunogenicity of an Investigational RSV Vaccine Candidate (Ad26.RSV.preF) in Adults 18 to 50 Years of Age, and RSV-seropositive Toddlers 12 to 24 Months of Age (NCT NCT03303625)

Last Updated: 2025-05-25

Results Overview

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. Solicited local AEs were precisely defined events that participants were specifically asked about and which were noted by participants in the diary. Solicited local AEs included erythema, swelling/induration, and pain/tenderness.

Recruitment status

COMPLETED

Study phase

PHASE1/PHASE2

Target enrollment

48 participants

Primary outcome timeframe

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

Results posted on

2025-05-25

Participant Flow

Participant milestones

Participant milestones
Measure	Cohort 0 (Adults): Ad26.RSV.preF Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.	Cohort 1 (Toddlers): Placebo RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.
Overall Study STARTED	8	4	24	12
Overall Study COMPLETED	6	4	24	12
Overall Study NOT COMPLETED	2	0	0	0

Reasons for withdrawal

Reasons for withdrawal
Measure	Cohort 0 (Adults): Ad26.RSV.preF Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.	Cohort 1 (Toddlers): Placebo RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.
Overall Study Withdrawal by Subject	2	0	0	0

Baseline Characteristics

A Study to Evaluate the Safety, Tolerability and Immunogenicity of an Investigational RSV Vaccine Candidate (Ad26.RSV.preF) in Adults 18 to 50 Years of Age, and RSV-seropositive Toddlers 12 to 24 Months of Age

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Total n=48 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	24 Participants n=5 Participants	12 Participants n=4 Participants	36 Participants n=21 Participants
Age, Categorical Between 18 and 65 years	8 Participants n=5 Participants	4 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	12 Participants n=21 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Sex: Female, Male Female	6 Participants n=5 Participants	2 Participants n=7 Participants	13 Participants n=5 Participants	8 Participants n=4 Participants	29 Participants n=21 Participants
Sex: Female, Male Male	2 Participants n=5 Participants	2 Participants n=7 Participants	11 Participants n=5 Participants	4 Participants n=4 Participants	19 Participants n=21 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Race (NIH/OMB) Asian	1 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 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	0 Participants n=4 Participants	0 Participants n=21 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Race (NIH/OMB) White	6 Participants n=5 Participants	4 Participants n=7 Participants	24 Participants n=5 Participants	11 Participants n=4 Participants	45 Participants n=21 Participants
Race (NIH/OMB) More than one race	1 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	1 Participants n=4 Participants	1 Participants n=21 Participants
Region of Enrollment FINLAND	0 Participants n=5 Participants	0 Participants n=7 Participants	10 Participants n=5 Participants	5 Participants n=4 Participants	15 Participants n=21 Participants
Region of Enrollment UNITED KINGDOM	8 Participants n=5 Participants	4 Participants n=7 Participants	13 Participants n=5 Participants	6 Participants n=4 Participants	31 Participants n=21 Participants
Region of Enrollment UNITED STATES	0 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	1 Participants n=4 Participants	2 Participants n=21 Participants

PRIMARY outcome

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

Population: The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Solicited Local Adverse Events (AEs) for 7 Days After First Vaccination	4 Participants	8 Participants	1 Participants	14 Participants

PRIMARY outcome

Timeframe: For 7 days after second vaccination on Day 29 (Up to Day 35)

Population: The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine. Here, 'N' (number of participant analyzed) signifies number of participants evaluable for this outcome measure.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=6 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Solicited Local Adverse Events (AEs) for 7 Days After Second Vaccination	4 Participants	6 Participants	0 Participants	14 Participants

PRIMARY outcome

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

Population: The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. Solicited systemic AEs included were for adult participants: fatigue, headache, myalgia, arthralgia, chills, nausea and fever (defined as body temperature \>=38 degree celsius \[°C\]; for pediatric participants: loss of appetite, vomiting, diarrhea, decreased activity/lethargy, irritability/crying and fever (i.e., body temperature \>=38 °C).

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Solicited Systemic Adverse Events for 7 Days After First Vaccination	10 Participants	8 Participants	1 Participants	23 Participants

PRIMARY outcome

Timeframe: For 7 days after second vaccination on Day 29 (Up to Day 35)

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. Solicited systemic AEs included were for adult participants: fatigue, headache, myalgia, arthralgia, chills, nausea and fever (defined as body temperature \>=38 degree celsius \[°C\]; for pediatric participants: loss of appetite, vomiting, diarrhea, decreased activity/lethargy, irritability/crying and fever (i.e., body temperature \>=38 °C).

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=6 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Solicited Systemic Adverse Events for 7 Days After Second Vaccination	9 Participants	4 Participants	1 Participants	22 Participants

PRIMARY outcome

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

Population: The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. Unsolicited adverse events included all adverse events for which the participant is not specifically questioned in the participant diary.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Unsolicited Adverse Events for 28 Days After First Vaccination	8 Participants	5 Participants	0 Participants	11 Participants

PRIMARY outcome

Timeframe: For 28 days after second vaccination on Day 29 (Up to Day 56)

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. Unsolicited adverse events included all adverse events for which the participant is not specifically questioned in the participant diary.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=6 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Unsolicited Adverse Events for 28 Days After Second Vaccination	6 Participants	4 Participants	1 Participants	12 Participants

PRIMARY outcome

Timeframe: From Day 1 (post-vaccination) to end of the study (up to 2 years 4 months)

Population: The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.

An AE is any untoward medical occurrence in a clinical study participant administered a medicinal (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with study vaccine. SAE is any untoward medical occurrence that at any dose may result in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, is a suspected transmission of any infectious agent via a medicinal product.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=12 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Number of Participants With Serious Adverse Events (SAEs)	2 Participants	0 Participants	0 Participants	1 Participants

SECONDARY outcome

Timeframe: Day 1 (predose), Post-dose on Days 29, 57 and 211

Population: The Per-protocol Immunogenicity (PPI) set included all randomized and vaccinated participants for whom immunogenicity data were available, excluding participant samples with major protocol deviations expecting to impact the immunogenicity outcomes. Here, 'n' (number analyzed) signifies the number of participants evaluable at a specified timepoint.

RSV A2 strain neutralizing antibody titers of the vaccine-induced immune response was assessed through virus neutralization assay.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=9 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=3 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=17 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Respiratory Syncytial Virus (RSV) A2 Strain Neutralization Antibody Titers at Days 1, 29, 57 and 211 Day 1 (pre-dose)	187 Titers Interval 100.0 to 349.0	329 Titers Interval 252.0 to 431.0	547 Titers Interval 86.0 to 3489.0	121 Titers Interval 76.0 to 191.0
Respiratory Syncytial Virus (RSV) A2 Strain Neutralization Antibody Titers at Days 1, 29, 57 and 211 Post dose 1: Day 29	156 Titers Interval 68.0 to 358.0	1089 Titers Interval 483.0 to 2456.0	603 Titers Interval 101.0 to 3596.0	1608 Titers Interval 730.0 to 3544.0
Respiratory Syncytial Virus (RSV) A2 Strain Neutralization Antibody Titers at Days 1, 29, 57 and 211 Post dose 2: Day 57	198 Titers Interval 89.0 to 441.0	926 Titers Interval 485.0 to 1769.0	566 Titers Interval 114.0 to 2805.0	2235 Titers Interval 1586.0 to 3150.0
Respiratory Syncytial Virus (RSV) A2 Strain Neutralization Antibody Titers at Days 1, 29, 57 and 211 Post dose 2: Day 211	165 Titers Interval 70.0 to 387.0	704 Titers Interval 325.0 to 1526.0	574 Titers Interval 139.0 to 2374.0	1164 Titers Interval 734.0 to 1847.0

SECONDARY outcome

Timeframe: Pre-fusion on Days 1, 29, 57 and 211

Population: The PPI set included all randomized and vaccinated participants for whom immunogenicity data were available, excluding participant samples with major protocol deviations expecting to impact the immunogenicity outcomes. Here, 'n' (number analyzed) signifies the number of participants evaluable at a specified timepoint.

GMT (ELISA units per liter \[EU/L\]) of RSV F protein in pre-fusion form as assessed by ELISA was reported.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=9 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=3 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=17 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Pre-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) at Days 1, 29, 57 and 211 Day 1	113 EU/L Interval 57.0 to 223.0	197 EU/L Interval 132.0 to 295.0	249 EU/L Interval 50.0 to 1234.0	59 EU/L Interval 36.0 to 97.0
Pre-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) at Days 1, 29, 57 and 211 Day 29	106 EU/L Interval 56.0 to 199.0	441 EU/L Interval 304.0 to 639.0	261 EU/L Interval 60.0 to 1138.0	1174 EU/L Interval 524.0 to 2630.0
Pre-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) at Days 1, 29, 57 and 211 Day 57	148 EU/L Interval 54.0 to 402.0	481 EU/L Interval 317.0 to 729.0	244 EU/L Interval 60.0 to 992.0	1918 EU/L Interval 1497.0 to 2456.0
Pre-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by Enzyme-linked Immunosorbent Assay (ELISA) at Days 1, 29, 57 and 211 Day 211	120 EU/L Interval 39.0 to 370.0	418 EU/L Interval 264.0 to 664.0	292 EU/L Interval 45.0 to 1895.0	924 EU/L Interval 639.0 to 1334.0

SECONDARY outcome

Timeframe: Post-fusion on Days 1, 29, 57 and 211

GMT (ELISA units per liter \[EU/L\]) of RSV F protein in post-fusion form as assessed by ELISA was reported.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=9 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=8 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=3 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=17 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Post-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by ELISA at Days 1, 29, 57 and 211 Day 1	94 EU/L Interval 46.0 to 190.0	196 EU/L Interval 112.0 to 346.0	191 EU/L Interval 19.0 to 1879.0	77 EU/L Interval 48.0 to 125.0
Post-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by ELISA at Days 1, 29, 57 and 211 Day 29	86 EU/L Interval 47.0 to 158.0	328 EU/L Interval 207.0 to 521.0	207 EU/L Interval 25.0 to 1738.0	686 EU/L Interval 371.0 to 1268.0
Post-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by ELISA at Days 1, 29, 57 and 211 Day 57	109 EU/L Interval 52.0 to 232.0	341 EU/L Interval 198.0 to 589.0	179 EU/L Interval 23.0 to 1370.0	863 EU/L Interval 630.0 to 1184.0
Post-Fusion RSV Fusion Protein (F-protein) Geometric Mean Titers (GMTs) as Assessed by ELISA at Days 1, 29, 57 and 211 Day 211	91 EU/L Interval 33.0 to 256.0	268 EU/L Interval 142.0 to 507.0	181 EU/L Interval 18.0 to 1870.0	420 EU/L Interval 306.0 to 576.0

SECONDARY outcome

Timeframe: Day 1 (predose) and Post-dose on Days, 29, and 57

Population: PPI set: all randomized and vaccinated participants for whom immunogenicity data were available, excluding participant samples with major protocol deviations expecting to impact immunogenicity outcomes. 'N' (number of participants analyzed)=number of participants who were evaluable for this outcome measure, 'n' (number analyzed)=number of participants evaluable at specified timepoint and '0' in number analyzed field=none of participants were applicable for evaluation at specified time point.

Total cytokine response (CD4, CD8, Th1 and Th2 Cytokines) after in vitro RSV F protein peptide stimulation was reported as the percentage of CD4+ and CD8+ T cells that produce at least 1 of 3 cytokines.

Outcome measures

Outcome measures
Measure	Cohort 1 (Toddlers): Placebo n=8 Participants RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.	Cohort 0 (Adults): Ad26.RSV.preF n=4 Participants Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=3 Participants Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=14 Participants Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD4: Day 1	0.050 Percentage of cytokine cell subsets Interval 0.015 to 0.079	0.058 Percentage of cytokine cell subsets Interval 0.057 to 0.067	0.054 Percentage of cytokine cell subsets Interval 0.048 to 0.108	0.030 Percentage of cytokine cell subsets Interval 0.013 to 0.095
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD4: Day 29	0.074 Percentage of cytokine cell subsets Interval 0.056 to 0.123	0.168 Percentage of cytokine cell subsets Interval 0.1 to 0.21	0.058 Percentage of cytokine cell subsets Interval 0.051 to 0.082	0.089 Percentage of cytokine cell subsets Interval 0.062 to 0.131
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD4: Day 57	—	0.148 Percentage of cytokine cell subsets Interval 0.115 to 0.351	0.039 Percentage of cytokine cell subsets Interval 0.024 to 0.116	—
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD8: Day 1	0.041 Percentage of cytokine cell subsets Interval 0.025 to 0.081	0.041 Percentage of cytokine cell subsets Interval 0.033 to 0.084	0.075 Percentage of cytokine cell subsets Interval 0.005 to 0.141	0.033 Percentage of cytokine cell subsets Interval 0.024 to 0.049
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD8: Day 29	0.053 Percentage of cytokine cell subsets Interval 0.016 to 0.11	0.145 Percentage of cytokine cell subsets Interval 0.08 to 0.233	0.092 Percentage of cytokine cell subsets Interval 0.022 to 0.105	0.077 Percentage of cytokine cell subsets Interval 0.024 to 0.116
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 CD8: Day 57	—	0.081 Percentage of cytokine cell subsets Interval 0.07 to 0.211	0.062 Percentage of cytokine cell subsets Interval 0.003 to 0.185	—
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th1: Day 1	0.018 Percentage of cytokine cell subsets Interval 0.011 to 0.027	0.045 Percentage of cytokine cell subsets Interval 0.028 to 0.065	0.054 Percentage of cytokine cell subsets Interval 0.031 to 0.096	0.007 Percentage of cytokine cell subsets Interval 0.003 to 0.022
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th1: Day 29	0.028 Percentage of cytokine cell subsets Interval 0.017 to 0.055	0.098 Percentage of cytokine cell subsets Interval 0.04 to 0.146	0.049 Percentage of cytokine cell subsets Interval 0.037 to 0.057	0.034 Percentage of cytokine cell subsets Interval 0.025 to 0.078
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th1: Day 57	—	0.112 Percentage of cytokine cell subsets Interval 0.083 to 0.302	0.039 Percentage of cytokine cell subsets Interval 0.008 to 0.061	—
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th2: Day 1	0.004 Percentage of cytokine cell subsets Interval 0.001 to 0.005	0.006 Percentage of cytokine cell subsets Interval 0.001 to 0.016	0.001 Percentage of cytokine cell subsets Interval 0.001 to 0.002	0.002 Percentage of cytokine cell subsets Interval 0.001 to 0.004
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th2: Day 29	0.003 Percentage of cytokine cell subsets Interval 0.002 to 0.007	0.003 Percentage of cytokine cell subsets Interval 0.002 to 0.006	0.001 Percentage of cytokine cell subsets Interval 0.001 to 0.001	0.005 Percentage of cytokine cell subsets Interval 0.001 to 0.007
Percentage of Cytokine Subsets (CD4, CD8, Th1 and Th2 Cytokines) to Evaluate Total Cytokine Response at Days 1, 29 and 57 Th2: Day 57	—	0.003 Percentage of cytokine cell subsets Interval 0.001 to 0.022	0.001 Percentage of cytokine cell subsets Interval 0.001 to 0.001	—

Adverse Events

Cohort 0 (Adults): Ad26.RSV.preF

Serious events: 0 serious events

Other events: 6 other events

Deaths: 0 deaths

Cohort 0 (Adults): Placebo

Serious events: 0 serious events

Other events: 1 other events

Deaths: 0 deaths

Cohort 1 (Toddlers): Ad26.RSV.preF

Serious events: 1 serious events

Other events: 19 other events

Deaths: 0 deaths

Cohort 1 (Toddlers): Placebo

Serious events: 2 serious events

Other events: 10 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Cohort 0 (Adults): Ad26.RSV.preF n=8 participants at risk Adult participants aged greater than or equal to (\>=) 18 years to less than or equal to (\<=) 50 years received a single intramuscular (IM) injection of adenovirus serotype 26 respiratory syncytial virus e pre-fusion conformation stabilized F-protein (Ad26.RSV.preF) at dose of 1\*10\^11 viral particles (vp) on Day 1 and Day 29.	Cohort 0 (Adults): Placebo n=4 participants at risk Adult participants aged \>=18 years to \<=50 years received a single IM injection of placebo matching to Ad26.RSV.preF (1\*10\^11 vp) on Day 1 and Day 29.	Cohort 1 (Toddlers): Ad26.RSV.preF n=24 participants at risk Respiratory syncytial virus (RSV) seropositive toddler participants aged \>=12 to \<=24 months received a single IM injection of Ad26.RSV.preF at dose of 5\*10\^10 vp on Day 1 and Day 29.	Cohort 1 (Toddlers): Placebo n=12 participants at risk RSV seropositive toddler participants received a single IM injection of placebo matching to Ad26.RSV.preF (5\*10\^10 vp) on Day 1 and Day 29.
Infections and infestations Cellulitis	0.00% 0/8 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/4 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	4.2% 1/24 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/12 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.
Nervous system disorders Syncope	0.00% 0/8 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/4 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/24 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	8.3% 1/12 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.
Respiratory, thoracic and mediastinal disorders Wheezing	0.00% 0/8 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/4 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	0.00% 0/24 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.	8.3% 1/12 • From Day 1 (post-vaccination) up to end of the study (up to 2 years 4 months) The safety analysis set included all participants who were randomized and received at least 1 dose of study vaccine.

Other adverse events

Additional Information

Trial Physician

Janssen Vaccines and 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