A Study to Learn About the Amount of the Study Medicine (Sisunatovir) in Blood and Its Safety in Infants and Children With Pneumonia Caused by RSV

University of Witwatersrand (WITS) - Vaccines and Infectious Diseases Analytics (VIDA), Johannesburg

Monti Clinical Research Centre, Mdantsane

Washington University School of Medicine, St Louis

Kaiser Permanente Los Angeles Medical Center, Los Angeles

Kaiser Permanente, Los Angeles

Kojunkai Daido Hospital, Nagoya

Nintenkai Kagoshima Children's Hospital, Hioki

Yamanashi Prefectural Central Hospital, Kofu

Osaka City General Hospital, Osaka