Pilot Treatment as Prevention for HCV Among Persons Who Actively Inject Drugs

Inclusion Criteria: 1. ≥18 years of age; 2. 2 consecutive positive HCV RNA tests at least 6 months after estimated date of infection; 3. HCV genotype 1; 4. HCV RNA \<6 million copies by Roche TaqMan Assay 5. No evidence of hepatic cirrhosis (as determined by two indices: Fib4\<3.25-an accurate test for detecting cirrhosis based on age, AST, ALT and platelets \[sensitivity/specificity 76-100/82-91%\], confirmed by the fibrosis-cirrhosis index (FCI)\<1.25 based on ALT, bilirubin, albumin and platelets \[sensitivity/specificity 86/100%\]); 6. Drug injection in past 30 days by self-report and physical exam evidence of injection drug use (e.g. track marks), 7. injected with others in past 12 months by self-report; 8. Lab values within acceptable range (platelets\>50,000, creatinine clearance by Cockroft-Gault\>30mL/min, hemoglobin \>10g/dL, INR\<1.5 x upper limit of normal (ULN) unless stable on anticoagulant regimen or known hemophilia, AST/ALT\<10 x ULN); 9. Able to speak English; 10. No plans to leave San Francisco area for at least 9 months and either lives or works in San Francisco, or travels to San Francisco at least weekly; 11. for women of childbearing age, pregnancy test negative, not actively nursing, and agree to use birth control during treatment (although LDV-SOF has a "B" rating, consistent with no known evidence of harm, treatment is not urgent for these patients so we will err on the side of caution). Exclusion Criteria: 1. HIV+ by rapid test or pooled viral load; 2. HBV surface antigen +; 3. Non-definitive HCV genotype results; 4. Previously received treatment for HCV (interferon, ribavirin, or DAA); 5. Taking medications that affect pharmacokinetics of LDV-SOF (proton-pump inhibitors, anticonvulsants \[phenobarbital, phenytoin, carbamazepine, oxcarbazepine\], rifamycins, rosuvastatin, herbs \[St. John's wort, silymarin, echinacea\]); 6. History of any of the following: 1. Current gastrointestinal disorder or post-operative condition that could interfere with the absorption of the study drug 2. History of hepatic decompensation (i.e., ascites, encephalopathy or variceal hemorrhage) 3. History of solid organ or bone marrow transplantation. 4. Current treatment for cancer 7. Chronic liver disease for non HCV reason, except iron overload (e.g., Wilson's disease, alfa 1 antitrypsin deficiency, cholangitis); 8. Use of any prohibited concomitant medications as described in Section 5.2 within 21 days of the Day 1 visit; and 9. Known hypersensitivity to LDV, SOF, the metabolites, or formulation excipients. 10. No other conditions that preclude study involvement as determined by PI.