Safety and Efficacy of Ledipasvir/Sofosbuvir Fixed Dose Combination +/- Ribavirin in Adolescents and Children With Chronic HCV-Infection

The primary objective of the PK Lead-in Phase of the study is to evaluate the steady state pharmacokinetics (PK) and confirm the dose of ledipasvir/sofosbuvir (LDV/SOF) fixed dose combination (FDC) in hepatitis C virus (HCV)-infected pediatric participants. The PK Lead-in Phase will also evaluate the safety, tolerability, and antiviral activity of 10 days of dosing of LDV/SOF FDC in HCV-infected pediatric participants. The Treatment Phase will be initiated by age cohort after confirmation of age-appropriate LDV/SOF FDC dosage levels. Participants from the PK Lead-in Phase will immediately rollover into the Treatment Phase with no interruption of study drug administration. The primary objective of the Treatment Phase is to evaluate the antiviral efficacy, safety, and tolerability of LDV/SOF FDC +/- ribavirin (RBV) for 12 or 24 weeks in pediatric participants with HCV. During screening, participants will receive placebo to match LDV/SOF FDC to assess ability to swallow tablets.