Study to Evaluate Safety and Antiviral Activity of Doses of JNJ-53718678 in Children (>=28 Days to <=3 Years) With Respiratory Syncytial Virus Infection
Condition: Respiratory Syncytial Virus Infections
MeSH terms: Infections; Communicable Diseases; Virus Diseases; Respiratory Syncytial Virus Infections
Intervention: JNJ-53718678; Placebo
Intervention description: Participants will receive JNJ-53718678 (high dose or low dose) orally twice daily for 7 days.; Participants will receive matching placebo (high volume or low volume) orally twice daily for 7 days.
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Enrollment: 246.0
Sex: All
Minimum age: 28 Days
Maximum age: 3 Years
Healthy volunteers: No

Summary:

      The purpose of this study is to evaluate the antiviral activity, clinical outcomes, safety,
      tolerability, and pharmacokinetic/pharmacodynamic relationships of different oral dose levels
      of JNJ-53718678 in children greater than or equal to 28 days and less than or equal to 3
      years of age with respiratory syncytial virus (RSV) disease (hospitalized participants
      [Cohort 1] or outpatients [Cohort 2]).
    

Eligibility criteria:

        Inclusion Criteria:

          -  Informed consent form (ICF) must be given

          -  Laboratory diagnosis of respiratory syncytial virus (RSV) infection

          -  The participant has an acute respiratory illness

          -  The time of onset of RSV symptoms to the anticipated time of randomization must be
             less than or equal to (<=) 5 days

          -  Except for the RSV-related illness, the Participant must be medically stable in case
             of allowed co-morbid conditions

          -  The participant must have been assessed per local public health practice and
             considered not to have Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
             infection during this respiratory infection

        Exclusion Criteria:

          -  The participant is less than (<) 3 months postnatal age at screening and was born
             prematurely (i.e, <37 weeks and 0 days of gestation) OR if the participant weighs <2.4
             kilogram (kg) or greater than (>) 16.8 kg

          -  Participant is considered by the investigator to be immunocompromised within the past
             12 months

          -  Participant unwilling or unable to undergo mid-turbinate nasal swab procedures

          -  Participant is receiving chronic home oxygen therapy at screening

          -  Participant has other clinically significant abnormal electrocardiogram (ECG) findings
             not consistent with the present risk factor for severe RSV disease (if applicable) in
             the study population, as judged by the investigator based on the machine read ECG
             results at screening

          -  The participant has a QTcF interval greater than (>)450 millisecond (ms) per the
             machine read (mean of triplicate) parameter result confirmed by repeat triplicate ECG
             recording during screening