A Two-Part Infant Study for Early Diagnosis of Respiratory Syncytial Virus (RSV) and Evaluation of JNJ-53718678 in RSV Acute Respiratory Tract Disease

The purpose of this two-part designed study is to assess in the setting of a planned early interception of pediatric RSV disease, early viral and disease kinetics (observational stage) and the antiviral effects of an Respiratory Syncytial Virus (RSV) fusion inhibitor, JNJ-53718678 (interventional stage). In the observational stage the infant is closely monitored for early symptoms by the parent(s)/caregiver(s) and thus may be brought in for diagnosis earlier than in the typical setting.