A Study to Investigate How Respiratory Syncytial Virus (RSV) Infection Develops and Changes Over Time in Pediatric Participants

Key Inclusion Criteria: * Participant who is presenting within 5 days of onset of clinical signs at the time of informed consent. * Participant is diagnosed with RSV within 5 days of sign onset. * Participant's caregiver must be able to complete daily Observer Reported Outcomes (ObsROs) and collect nasal swabs Key Exclusion Criteria: * Participant is hospitalized for reasons other than RSV infection. * Participant is considered by the PI to be immunocompromised, due to an underlying medical condition or medical therapy. * Participant has or has had a confirmed respiratory infection with another clinically relevant viral/bacterial pathogen within 14 days of study enrollment. * Participant underwent major surgery within 28 days prior to enrollment in the study or has planned major surgery within 15 days of expected study completion. Note: Other protocol defined Inclusion/Exclusion criteria may apply.