An Exploratory Study to Evaluate the Prophylactic Efficacy of a Single Immunization of Ad26.RSV.preF Against Respiratory Syncytial Virus Infection in a Virus Challenge Model in Healthy 18 to 50 Year-old Adults

Peak viral load of RSV-A Memphis 37b was defined as the maximum viral load as determined by quantitative RT-PCR assay of nasal wash samples. Here, values below the lower limit of quantification (LLOQ) were imputed with zero.

Viral load determined by quantitative RT-PCR assay of nasal wash samples on Day 6 and Day 7 were reported. Here, values below the lower limit of quantification (LLOQ) were imputed with zero.

VL-AUC of RSV by the quantitative culture of nasal wash samples on Day 6 and Day 7 were determined.

pfu*h/mL stands for plaque-forming units hour per millilitre.

Symptomatic RSV infection is defined in two ways (Conservative and Liberal). Conservative: participant had 2 or more quantifiable RT-PCR measurements on different samples, with one of following: symptoms of 2 different categories of subject symptom card (SSC) (Upper Respiratory [runny/stuffy nose, sneezing, sore throat, earache], Lower Respiratory [cough, shortness of breath, chest tightness, wheeze], Systemic [malaise, headache, muscle and/or joint ache]) regardless of grade and assessment timepoint or Grade 2 symptom from any category; Liberal (RT-PCR): had 2/more quantifiable RT-PCR measurements, with clinical symptom of any severity.

The total clinical symptom score was determined as the sum of the scores (grades) ranges from 0 (no symptom) to 52 (severe symptoms) of the 13 self-reportable symptoms on the SSC. Clinical symptoms includes runny nose, stuffy nose, sneezing, sore throat, ear ache, malaise, headache, muscle and/or joint ache, chilliness/ feverishness, cough, chest tightness, shortness of breath and wheeze. For every separate symptom, the score ranges from 0 (I have no symptom) to 4 (its quite bothersome most of the times and stop from participating in activities).

The weight mucous over time was determined in grams using eCRF forms. Participants were given pre-weighed packets of paper tissues. After each tissue was used for nose blowing or sneezing, the participants should store them in an airtight plastic bag to calculate the weight of mucus from Day 0 to Day 12. All paper tissues used by each participant were collected for each 24-hour period up to Day 12, to determine daily mucus weight.

Number of tissues used by participant per time point were reported using eCRF forms. Participants were given pre-weighed packets of paper tissues. After each tissue was used for nose blowing or sneezing, the participants should store them in an airtight plastic bag to calculate the number of tissues used from Day 0 to Day 12. All paper tissues used by each participant were collected for each 24-hour period up to Day 12, to determine daily number of tissues used.

Unsolicited AEs are all AEs for which participants were specifically not questioned in the participant diary. 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.

A SAE is an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly.

Solicited local AEs: erythema, swelling/induration, and pain/tenderness. Solicited systemic AEs: fatigue, headache, myalgia, arthralgia, chills, nausea and fever.

Percentage of participants with vital signs abnormalities were reported. Vital signs measurements included body temperature (measured in degree celsius from less than [<] 37.5 to <39.5), respiratory rate, systolic and diastolic blood pressure, and pulse rate, which were graded by FDA Toxicity Grading Scale Grade 0 (=no grade), Grade 1 (=mild), Grade 2 (=moderate), Grade 3 (=severe) and Grade 4 (=potentially life-threatening).

ECG parameters included heart rate, PR, QRS, QTcB, QTcF, and the uncorrected QT interval which were graded by FDA Toxicity Grading Scale Grade 0 (=no grade), Grade 1 (=mild), Grade 2 (=moderate), Grade 3 (=severe) and Grade 4 (=potentially life-threatening).

Percentage of participants with clinical laboratory abnormalities were reported. The biochemical and hematological parameters analyzed were- Alanine aminotransferase (AA), Alkaline phosphatase (AP), Aspartate aminotransferase (AsP), Hyperkalemia, Hypernatremia, Hypoglycemia, Hypophosphatemia, Hemoglobin, Neutrophils, White blood cell (WBC) - increase and Urine protein, which were graded by FDA Toxicity Grading Scale Grade 0 (=no grade), Grade 1 (=mild), Grade 2 (=moderate), Grade 3 (=severe) and Grade 4 (=potentially life-threatening).