Durability of Virologic Response and/or Viral Resistance Patterns in Participants With Chronic Hepatitis C Who Have Been Previously Treated With Grazoprevir (MK-5172) (MK-5172-017)

This is a three-year (except for participants with chronic kidney disease \[CKD\] or cirrhosis) multicenter study to follow participants who received at least one dose of grazoprevir (MK-5172) in a previous study to determine whether they remain hepatitis C virus (HCV)-Ribonucleic acid (RNA) negative over time, and to determine if they have developed antiviral resistance. The study will also evaluate long-term adverse events in this population. Participants from MK-5172-052 (NCT02092350) with CKD or cirrhosis will be followed for five years.

As of Amendment 03, the study design is revised such that continued enrollment will only be for participants who failed prior therapy with a grazoprevir regimen. Participants with CKD enrolled from MK-5172-052 (NCT02092350) will continue enrollment regardless of prior treatment-response and remain in this study for five years, while participants enrolled from all other studies with HCV RNA less than the lower limit of quantitation (LLOQ) will be discontinued and end their participation after the next scheduled visit. In addition, participants who receive other HCV treatments concurrent with this follow-up study or received other HCV treatments prior to this study will be discontinued and their data excluded from analysis.

As of Amendment 04, the protocol has been updated to include enrollment of pediatric participants from protocol MK-5172-079 (NCT03379506). Enrollment is limited to participants who experienced virologic failure associated with 1 or more treatment-emergent resistant associated substitutions (RASs) present at 12 weeks after receiving grazoprevir treatment in prior treatment study MK-5172-079 (NCT03379506).

Eligibility Criteria:
Inclusion Criteria:

* Previously participated in a HCV treatment protocol that included grazoprevir in the treatment regimen
* Must enroll in the present study within three months of the last study visit of their previous protocol in which they received a grazoprevir-containing regimen
* For Amendment 03: Adult participants must have received a grazoprevir-containing regimen in a prior trial and have been identified as having failed therapy in that study
* For Amendment 04: Pediatric participants must have received at least 1 dose of a grazoprevir-containing regimen and experienced virologic failure with 1 or more associated treatment-emergent RASs at Follow-up Week 12 in MK-5172-079 (NCT03379506)

Exclusion Criteria:

* Has received HCV therapy after completion of the protocol-defined grazoprevir treatment trial regimen and before or after entry into this follow-up study
* For Amendment 03: Has failed therapy due to re-infection, defined as an HCV RNA sample with a different genotype than the baseline genotype in the prior treatment study, or an HCV RNA sample determined to be reinfection by phylogenetic analysis with comparison to the baseline sequence in the prior treatment study
* For Amendment 03: Has failed therapy and received retreatment with HCV therapy, except in the case where they were re-treated in a Merck-sponsored protocol