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.

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.

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.

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.

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.

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.

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.

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.

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. Unsolicited AEs were precisely defined events that participants were not asked about and which were not noted by participants in the diary.

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.

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. Unsolicited AEs were precisely defined events that participants were not asked about and which were not noted by participants in the diary.

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.

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.

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.

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

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.

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

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.

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

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.

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.

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.

Number of participants with severe RSV-LRTI were reported.

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.