Pegasys Long-Term Anti-Fibrotic Effect Co-Infection Trial (PERFECT)

Inclusion Criteria: * Serologic evidence of chronic hepatitis C infection by anti-HCV antibody test * Received peginterferon alfa-2a for at least 12 weeks and either did not reach a 2-log drop in HCV RNA after 12 weeks of treatment, did not reach an undetectable HCV RNA after 24 weeks of treatment, or reached undetectable HCV RNA that was detectable again at the end of 48 weeks of treatment * Detectable serum HCV RNA at Screening * Serologic evidence of HIV infection by HIV RNA detection * CD4 cell count greater than or equal to (\>/=) 100 cells/mcL during therapy with peginterferon alfa-2a plus ribavirin for at least 12 weeks * Stable HIV status and, if on antiretroviral therapy, a stable regimen for at least 6 weeks prior to Baseline * Compensated liver disease * No evidence of hepatocellular carcinoma Exclusion Criteria: * Pregnant or breastfeeding * Antineoplastic or immunomodulatory treatment within 6 months prior to first dose * Any investigational drug within 6 weeks prior to first dose * Positive for hepatitis A immunoglobulin M antibody * Severe neutropenia or thrombocytopenia at Screening while still on therapy with peginterferon alfa-2a plus ribavirin * Severe psychiatric or neurologic comorbidity * History of any significant medical conditions, such as immune disorders or disease of the major organ systems * Uncontrolled thyroid disease * Severe retinopathy * Evidence of drug abuse