Study to Evaluate Adverse Events and Change in Disease Activity in Adult and Adolescent Participants With Acute Hepatitis C Virus (HCV) Infection on Treatment With Oral Tablets of Glecaprevir (GLE)/Pibrentasvir (PIB)

Inclusion Criteria: * Evidence of acute HCV infection prior to enrollment, defined as a physician diagnosis of acute HCV infection, quantifiable HCV ribonucleic Acid (RNA) at screening, and at least 1 of the following: * Negative anti-HCV antibody, HCV RNA and/or HCV core antigen followed by a positive HCV RNA or HCV core antigen all within an 8-month period prior to screening; OR * Negative anti-HCV antibody, HCV RNA and/or HCV core antigen followed by a positive HCV RNA or HCV core antigen all within an 11-month period prior to screening; AND risk behavior for HCV infection within 6 months prior to positive HCV RNA or HCV core antigen; OR * Clinical signs and symptoms compatible with acute hepatitis \[alanine aminotransferase (ALT) \> 5 × upper limit of normal (ULN) and/or jaundice\] in the absence of a history of chronic liver disease or other cause of acute hepatitis and positive HCV RNA or HCV core antigen all within an 8-month period prior to screening; AND risk behavior for HCV infection within 6 months prior to positive HCV RNA or HCV core antigen; OR * Negative anti-HCV antibody with a positive HCV RNA or HCV core antigen within a 5-month period prior to screening. * Absence of hepatocellular carcinoma (HCC), for participants with cirrhosis, or with indeterminate cirrhosis status, as indicated by a negative ultrasound, computed tomography (CT) scan or magnetic resonance imaging (MRI) within 3 months prior to screening or a negative ultrasound at screening. Participant who has a positive ultrasound result suspicious of HCC followed by a subsequent negative CT scan or MRI or biopsy result will be eligible for the study. * Participants documented as having no cirrhosis or as having compensated cirrhosis. Exclusion Criteria: * Participants with prior treatment, including interferon for this HCV infection. * History of liver decompensation.