RSV is recognized as major respiratory pathogen in infants and young children and causes upper and lower respiratory illness among all age groups, often going undiagnosed. Immunocompromised (IC) participants have a reduced ability to combat infection due to an impaired or weakened immune system. Within the IC population, HSCT recipients are generally regarded as having a particularly high risk for more severe disease caused by RSV, representing a substantial unmet need for antiviral treatment of RSV infections in this participant population. JNJ-53718678 is an investigational, potent, small molecule, respiratory syncytial virus (RSV)-specific fusion inhibitor. The study will include a Screening Period (Day -2 to Day 1), a Treatment Period (Day 1 to Day 21), and a Follow-up Period (1 year). Assessments like chest X-ray, pulse/heart rate, respiratory rate, electrocardiogram (ECG), etc will be performed. Safety and efficacy will be assessed through the study. The total study duration for each participant will be approximately 49 days.
