IFNA1 and chronic hepatitis: In Japan, telaprevir was approved in November 2011 as an antiviral agent for the treatment of patients with chronic hepatitis caused by genotype 1 HCV infection, both those without a previous history of combined Peg-IFN plus ribavirin therapy [12] and those who developed relapse or showed no response to previous combined Peg-IFN plus ribavirin therapy [13].