The rate of sustained virologic response was 94 % ( 95 % confidence interval [ CI ] , 90 to 97 ) with 8 weeks of ledipasvir-sofosbuvir , 93 % ( 95 % CI , 89 to 96 ) with 8 weeks of ledipasvir-sofosbuvir plus ribavirin , and 95 % ( 95 % CI , 92 to 98 ) with 12 weeks of ledipasvir-sofosbuvir .