Short Duration Therapy of Acute Hepatitis C Genotypes 1 or 4

Inclusion Criteria: 1. Adult ≥18 years. 2. A recent acute HCV infection \[defined by (i) detectable HCV RNA within 6 months after a negative HCV RNA or HCV serology test OR (ii) detectable HCV RNA and acute clinical hepatitis within 5 months prior to screening visit (ALT ≥250 IU/L with normal ALT within the preceding 8 months OR ALT ≥500 IU/L with either no measured ALT or with abnormal ALT within the preceding 8 months)\] or reinfection \[defined by documented de novo infection after prior clearance post-treatment (defined by one negative HCV RNA ≥6 months after end of treatment) or spontaneously (defined by two negative HCV RNA a minimum of 6 months apart OR documented infection with a new viral strain, confirmed by phylogenetic or genotypic analysis)\] within 5 months prior screening OR (iii) patients having reported a risk factor for HCV contamination (traumatic sexual intercourse, intranasal, rectal or intravenous drug use) ≥6 months AND presenting a negative HCV RNA or HCV serology test within 12 months. 3. Infection with HCV genotype 1 or 4 (confirmed at screening visit or by using a previous biological test performed 1 to 4 weeks before week 0). 4. Plasma HCV-RNA ≥ 1000 IU/mL (confirmed at screening visit or by using a previous biological test performed 1 to 4 weeks before week 0). 5. Confirmed HIV infection (only for HIV co-infected patients). 6. Without HIV treatment or with an authorized stable HIV treatment for at least two weeks (only for HIV co-infected patients). 7. Body weight ≥40 kg and ≤125 kg. 8. Female patients with child-bearing potential and their heterosexual partners must use adequate contraception from the date of screening until 30 days after administration of the last dose of study drug. Male participants must agree to consistently and correctly use a condom, while their female partner must use adequate contraception from the date of screening until 30 days after administration of the last dose of study drug. 9. Informed and signed consent. 10. Patients with Health insurance (Sécurité Sociale or Couverture Médicale Universelle). Exclusion Criteria: 1. Opportunistic infections (stage C), active or occurred within 6 months prior to baseline. 2. Primary HIV infection. 3. Co-infection with Hepatitis B virus (HBsAg-positive) without appropriate treatment (TDF or TAF) for at least 2 weeks. 4. Confirmed cirrhosis (before acute HCV diagnosis). 5. Any other causes of acute hepatitis. 6. Pregnant or breast-feeding women. 7. Liver transplant recipients. 8. Evolutive malignancy. 9. Patients with a history of non-adherence, who will be at risk of being unable to respect the study follow-up timetable. 10. Patients participating in another clinical trial (with an experimental treatment) or within an exclusion period of a previous clinical trial at screening. 11. Patients under legal gardianship or incarcerated. 12. Hemaglobulin \<10 g/dL (female) or \<11g/dL (male). 13. Platelet count \<50,000/mm3. 14. Neutrophil count \< 750/mm3. 15. Other antiretroviral drugs than those allowed in the study. 16. Contra-indications to grazoprevir and/or elbasvir or to any of the excipients listed in the summary of the product characteristics. 17. Contra-indicated treatment likely to interfere with the study drugs as listed in the summary of the product characteristics.