Patient description: The patient is a 55-year-old man diagnosed with HCV 2 years ago and the recent coinfection with HBV. His past medical history is non-significant. He is on IFN, RBV and direct antiviral drugs for the past 6 months. The patient takes no other medications. His medical records show previous positive HCV RNA tests and a positive enzyme immunoassay for anti-HCV-antibodies. The recent biopsy was negative for hepatocellular carcinoma and was only remarkable for chronic inflammation compatible with a chronic viral hepatitis. There is no evidence of alcoholic liver disease, bleeding from esophageal varices, hemochromatosis, autoimmune hepatitis, or metabolic liver disease. He is an alert male with no acute distress. His BP: 130/75, HR: 90/min and BMI: 27. His abdomen is soft with no ascites or tenderness. The lower extremities are normal with no edema.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Hepatitis C Subjects must meet all of the following to be eligible to participate in this study: 1. Participants have voluntarily signed the informed consent form. 2. 18 years of age or older. 3. Detectable HCV RNA at screening (>10,000 IU/ml), and in the opinion of the investigator is unlikely to demonstrate spontaneous viral clearance 4. HCV genotypes 1-6. 5. HBsAg negative 6. Compensated liver disease (Child-Pugh A) 7. Negative pregnancy test at baseline (females of childbearing potential only). 8. Medically stable on the basis of physical examination, medical history and vital signs 9. Adequate English to provide reliable responses to the study questionnaires 10. All fertile males and females must be using effective contraception during treatment and during the 30 days after treatment end. 11. Recently acquired HCV infection (estimated duration of infection ≤12 months)* Recently acquired HCV infection as defined by: A) i) First anti-HCV Ab or HCV RNA positive within the previous 3 months and ii) Documented anti-HCV Ab negative within the 12 months prior to anti-HCV antibody positive result OR B) i) First anti-HCV Ab or HCV RNA positive within the previous 3 months and ii) Acute clinical hepatitis [jaundice or alanine aminotransferase (ALT)] > 10 X ULN) within the previous 6 months prior to first positive HCV antibody or HCV RNA, with no other cause of acute hepatitis identifiable OR C) For cases of recent HCV reinfection the following are required: Documented prior HCV antibody positive with HCV RNA negative on at least 2 occasions 6 months apart AND new HCV RNA positive within the previous 6 months *Estimated duration of infection based on midpoint between last antibody negative or HCV RNA and first antibody positive or HCV RNA in the case of seroconversion and 6 weeks prior to date of maximum ALT in the case of acute hepatitis. If co-infection with HIV is documented, the subject must meet the following 1. Antiretroviral (ARV) untreated for >8 weeks preceding screening visit with cluster of differentiation 4 (CD4) T cell count >500 cells/mm3 OR 2. On a stable ARV regimen for >8 weeks prior to screening visit, with CD4 T cell count >200 cells/mm3 and an undetectable plasma HIV RNA level Suitable ARV Tenofovir (TDF) and tenofovir alafenamide (TAF) Emtricitabine (FTC) Rilpivirine Dolutegravir Elvitegravir/cobicistat Contraindicated ARV Efavirenz 50% reduction in velpatasvir (GS-5816) exposure Didanosine  Subjects who meet any of the are not to be enrolled in this study. 1. History of any of the following: 1. Clinically significant illness (other than HCV) or any other major medical disorder that may interfere with the participant treatment, assessment or compliance with the protocol; participants currently under evaluation for a potentially clinically significant illness (other than HCV) are also excluded. 2. History of chronic pulmonary disease associated with functional limitation, severe cardiac disease, major organ transplantation or other evidence of severe illness, malignancy, or any other conditions which would make the patient, in the opinion of the investigator, unsuitable for the study 3. Solid organ transplant 4. Malignancy within 5 years prior to screening, with exception of specific cancers that may have been cured by surgical resection (basal cell skin cancer, etc.). Subjects under evaluation for possible malignancy are also excluded. 5. Significant drug allergy (such as anaphylaxis or hepatotoxicity). 2. Subject shows evidence of significant liver disease in addition to hepatitis C, which may but is not limited to drug or alcohol-related cirrhosis, autoimmune hepatitis, hemochromatosis, Wilson's disease, non-alcoholic steatohepatitis (NASH), or primary biliary cirrhosis 3. Subject has known cirrhosis 4. Any of the following lab parameters at screening: 1. Direct bilirubin > 1.5 x ULN 2. Platelets < 50,000/μL 3. Creatinine clearance (CLcr) < 60 mL/min 4. Haemoglobin < 11 g/dL for females ; < 12 g/dL for males 5. Albumin < 30g/L 5. Pregnant or nursing female. 6. Use of prohibited concomitant medications as described in section 5.2 in the protocol 7. Chronic use of systemically administered immunosuppressive agents (e.g. prednisone equivalent > 10 mg/day) 8. Known hypersensitivity to velpatasvir, sofosbuvir or formulation excipients. 9. Therapy with any anti-neoplastic or immunomodulatory treatment (including supraphysiologic doses of steroids and radiation) ≤6 months prior to the first dose of study drug. 10. Any investigational drug ≤6 weeks prior to the first dose of study drug. 11. Previous failure of therapy with sofosbuvir or an non-structural protein 5A (NS5A) inhibitor prior to the first dose of study drug. 12. Ongoing severe psychiatric disease as judged by the treating physician. 13. Frequent injecting drug use that is judged by the treating physician to compromise treatment safety. 14. Inability or unwillingness to provide informed consent or abide by the requirements of the study