Panama and El Salvador Children's Oseltamivir Study

This is a prospective, randomized, double-blind, placebo-controlled trial that will be conducted in tertiary care pediatric hospitals in El Salvador and Panama. The primary purpose of this study is to determine whether empiric oseltamivir phosphate treatment given at the time of hospital admission to children less than 10 years of age hospitalized with influenza can effectively reduce their illness severity. Additional objectives are to: 1) evaluate the tolerability of oseltamivir phosphate treatment, 2) evaluate the effect of oseltamivir treatment on viral clearance and development of oseltamivir-resistant influenza virus during and after treatment in children hospitalized with influenza, 3) estimate the direct and indirect costs of all-cause respiratory illness and influenza-associated respiratory illness requiring hospitalization, and 4) evaluate the effect of empiric oseltamivir treatment during the influenza season on these costs. The primary study hypothesis is that children with laboratory-confirmed influenza receiving empiric oseltamivir phosphate treatment initiated at the time of hospital admission will have a shorter duration of hospitalization and a shorter time to resolution of signs of severe respiratory illness compared to children receiving placebo. The secondary study hypotheses are that children with laboratory-confirmed influenza receiving oseltamivir phosphate treatment will have a reduction in the time to non-detectable influenza virus and influenza viral RNA and children with all-cause respiratory illness receiving oseltamivir phosphate will not be more likely to experience severe adverse events than children receiving placebo.