Treatment-nave adults ( @ years ) with chronic hepatitis C virus genotype @ infection ( hepatitis C virus RNA @ log@ IU/ml ) were randomized ( @:@ ) to simeprevir @mg once-daily with peginterferon -@ a/ribavirin for @ weeks then response-guided therapy with peginterferon -@ a/ribavirin for @ or @ weeks , or to placebo with peginterferon -@ a/ribavirin for @ weeks then peginterferon -@ a/ribavirin for @ weeks .