An orally available inhibitor of human respiratory syncytial virus (RSV) fusion protein (F protein), with potential antiviral activity. Upon oral administration of GS-5806, this agent specifically binds to F protein on the viral surface, which inhibits RSV F protein-mediated fusion with the host cell membrane and prevents viral entry. This blocks RSV replication, reduces viral load, and decreases the severity of the disease. RSV F protein, a viral surface glycoprotein, plays a key role in RSV fusion with and entry into target cells.