Pegylated interferon therapy has not been adequately evaluated in acute hepatitis C virus (HCV) infection. This randomized trial assessed the efficacy, safety, and timing of pegylated interferon alfa-2b for treatment of acute hepatitis C. One hundred seventy-five patients acutely infected with HCV were screened. Patients whose infection did not spontaneously resolve by week 8 were randomized to once weekly peginterferon alfa-2b monotherapy (1.5 microg/kg per week) started at weeks 8, 12, or 20 for a duration of 12 weeks. The primary endpoint was undetectable HCV RNA 24 weeks after the end of treatment (sustained virologic response [SVR]). All patients were followed for 48 weeks after cessation of therapy. One hundred twenty-nine subjects started treatment at week 8 (group A, n = 43), week 12 (group B, n = 43), or week 20 (group C, n = 43). By using an intent-to-treat analysis, the overall SVR rate was 87%. The SVR rates were 95%, 92%, and 76% with treatment onset at 8, 12, and 20 weeks, respectively. Overall, SVR rates were better for patients infected with genotypes 2, 3, and 4 than those infected with genotype 1. Earlier initiation of therapy improved SVR rates for patients infected with genotype 1 with high viral load. Peginterferon alfa-2b was well tolerated. Subjects with SVR maintained undetectable HCV RNA 48 weeks after therapy. Peginterferon alfa-2b monotherapy in acute hepatitis C induces high sustained virologic response rates, prevents chronic evolution, and is well tolerated. Initiation of treatment at week 8 or 12 results in higher sustained virologic rates than initiation at week 20.

Pegylated interferon α (PEG IFN-α) improves sustained virological response rates in chronic hepatitis C, but neither its role in acute hepatitis C nor the biologic basis for its action has been defined. This prospective study assessed the efficacy of PEG IFN-α treatment in acute hepatitis C in relation to the kinetics of hepatitis C virus (HCV)-specific CD4⁺ T cell responses during therapy and follow-up. Forty subjects with proven acute hepatitis C who received either PEG IFN-α plus ribavirin (n = 20) or PEG IFN-α monotherapy (n = 20) for 24 weeks in addition to 14 untreated subjects with acute hepatitis C were prospectively followed. Serum HCV RNA, HCV-specific CD4⁺ T cell responses, and cytokine production were measured before and during therapy and at follow-up and correlated to the outcome. The sustained virological response rate was 85% with PEG IFN-α/ribavirin combination and 80% with PEG IFN-α monotherapy. Five untreated subjects had spontaneous recovery. The frequency, magnitude, and breadth of HCV-specific CD4⁺ T helper 1 responses were significantly higher in treated subjects compared with untreated subjects with self-limited disease or subjects with chronic evolution. The CD4⁺ T cell responses were maintained in subjects with sustained virological responses and self-limited disease but fluctuated in those who developed chronic infection. In conclusion, PEG IFN-α therapy in acute hepatitis induces high rates of sustained virological response and prevents choronicity, probably through efficient early stimulation of multispecific HCV-specific CD4⁺ T helper 1 responses. (Hepatology 2004;39:1721-1731.)