This is a non-randomized, open-label study of a fixed dose combination (FDC) of elbasvir (50 mg) and grazoprevir (100 mg) (EBR/GZR or MK-5172A) in participants with chronic hepatitis C virus (HCV) genotype 1 (GT1) infection with advanced fibrosis with and without human immunodeficiency virus (HIV) co-infection. All participants will be either HCV treatment naïve (TN) or treatment experienced (TE).