 Influenza-related lower respiratory tract infection LRTI can cause serious illness or death in children younger than a year old. Only four medications are registered to treat influenza, and these do not have detailed recommendations for treating children younger than one year of age. One of these medications, oseltamivir, has no official recommendation for usage in children younger than one year of age, but it may be the best treatment for certain strains of influenza. A small number of children younger than one year of age have received oseltamivir in several countries with good clinical outcomes and apparently good tolerability. This study will test oseltamivir in children younger than one year of age to see if it is safe and effective. 