RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at baseline were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores.

Intent-to-Treat infected (ITT-i) analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection (positive test by central laboratory analysis) were excluded.

RSV-related complications were reported. The RSV-related complications included pulmonary complications (primary viral pneumonia, bronchitis, respiratory failure, secondary bacterial pneumonia, and exacerbations of underlying chronic pulmonary diseases [such as COPD and asthma]) and extrapulmonary complications (cardiovascular and cerebrovascular disease events, congestive heart failure [CHF] or exacerbation of underlying CHF, acute exacerbation of chronic kidney disease, severe dehydration, decompensation of previously controlled diabetes mellitus, and other airway infections). Complications after first intake of study drug were considered for this outcome measure.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded.

New antibiotic use, or new use or increased dose of systemic or inhaled corticosteroids and bronchodilators, or home oxygen supplementation were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded.

Unscheduled outpatient clinic visits, emergency room visits or hospitalization for respiratory infection were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded.

Percentage of participants meeting a composite endpoint of either developing RSV-related complications (pulmonary and extra-pulmonary) and/or needing RSV-related medical attendance was derived.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded.

An adverse events (AEs) is any untoward medical occurrence in a clinical study participant administered a pharmaceutical (investigational or non-investigational) product. An AE does not necessarily have a causal relationship with the intervention. Any AE which occurred at or after the initial administration of study intervention through the end of the study (that is, Day 35) was considered treatment-emergent.

Safety analysis set included all participants who took at least 1 dose of study intervention.

Abnormal clinical laboratory findings were reported. Laboratory abnormalities were determined as per division of microbiology and infectious diseases(DMID) toxicity as Grade 1:mild(transient or mild discomfort [less than {<} 48 hours]; no medical intervention/therapy required); Grade 2:moderate (mild to moderate limitation in activity-some assistance may be needed; no or minimal medical intervention/therapy required); Grade 3:severe (severe marked limitation in activity, some assistance usually required; medical intervention/therapy required, hospitalizations possible); Grade 4:life-threatening (extreme limitation in activity, significant assistance required; significant medical intervention/therapy required, hospitalization or hospice care probable). Only Grade 2 abnormalities are reported in this outcome measure. A treatment emergent abnormality is any abnormality not present at baseline and occurring post first administration or worsening versus baseline post first administration.

Safety analysis set included all participants who took at least 1 dose of study intervention.

Various ECG variables assessed were heart rate: abnormally low (less than or equal to [<=] 45 beats per minute [bpm]), abnormally high (greater than or equal to [>=] 120 bpm); PR interval: abnormally high (>=210 milliseconds [msec]); QRS interval: abnormally high (>=120 msec); QTc: borderline prolonged: >450 msec and <=480 msec, prolonged: >480 msec and <=500 msec, pathologicaly prolonged: >500 msec. A treatment emergent abnormality is any abnormality not present at baseline and occurring post first administration or worsening versus baseline post first administration.

Safety analysis set included all participants who took at least 1 dose of study intervention.

Abnormal vital parameters included pulse rate: abnormally low <=45 bpm, abnormally high >=120 bpm; Systolic Blood Pressure (SBP): abnormally low <=90 millimeter of mercury (mmHg), Grade 1 (mild): >140 mmHg to <160 mmHg, Grade 2 (moderate): >=160 mmHg to <180 mmHg, Grade 3 (severe): >=180 mmHg; Diastolic BP: abnormally low <=50 mmHg, Grade 1: >90 mmHg to <100 mmHg, Grade 2: >=100 mmHg to <110 mmHg, Grade 3: >=110 mmHg; Respiratory rate: Grade 1 (mild): 17-20 breaths per minute, Grade 2 (moderate): 21-25 breaths per minute, Grade 3 (severe): >25 breaths per minute, Grade 4 (potentially life threatening): intubation; Oxygen saturation: abnormally low: <95%; Temperature: abnormally high >38.0 degree celsius. A treatment emergent abnormality is any abnormality not present at baseline and occurring post first administration or worsening versus baseline post first administration.

Safety analysis set included all participants who took at least 1 dose of study intervention.

RSV viral load (subtype: RSV A and RSV B) was measured over time by quantitative reverse transcription polymerase chain reaction (qRT-PCR) in the nasal swab specimens collected at the clinic visits and at home. In this outcome measure, only those timepoints and RSV subtypes (A or B) for which individual participants had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure and 'n' (number analyzed) represents number of participants evaluable at the specified timepoints.

Plasma concentration of rilematovir was reported. This outcome measure was planned to be analyzed for specified arm only. In this outcome measure, only those timepoints for which individual participants had data were reported.

Pharmacokinetic (PK) analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 3 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-I analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 8 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 14 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 21 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 28 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.

RSV LRTD symptoms (cough, short of breath, wheezing, coughing up phlegm [sputum]) as assessed by the RiiQ symptom scale score at Day 35 were reported. The RiiQ symptom scale was a 13-items questionnaire rated on a 4-point scale. Each symptom was rated on a scale of 0 to 3 where 0=None, 1=Mild, 2=Moderate, and 3=Severe. Higher scores indicated greater severity. The LRTD symptom score was calculated as the mean of the LRTD symptom scores. In this outcome measure, only those individual participants who had data were reported.

ITT-i analysis set included all participants who were randomized and treated (at least one dose) and had RSV infection confirmed by central laboratory analysis. Participants with confirmed SARS-CoV-2 infection (positive test by central laboratory analysis) were excluded. Here, 'N' (number of participants analyzed) signifies number of participants with available data for this outcome measure.