Virology Follow up Study in Subjects Previously Treated With Telaprevir

Inclusion Criteria: * Received at least 1 dose of telaprevir-based treatment in 1 of the following clinical studies: VX05-950-104, VX05-950-104EU, VX06-950-106, VX06-950-107, VX07-950-108, VX08-950-111, or VX-950-TiDP24-C216 * Have baseline HCV viral sequencing data available from previous telaprevir study Exclusion Criteria: * May not be currently participating in the antiviral follow-up period of an ongoing telaprevir trial. (Note: Subjects who have completed the required antiviral follow-up period but are still participating in the collection of patient-reported outcomes data for their previous telaprevir study may be eligible.) * For subjects participating in ongoing studies at the time of enrollment, have more than 90 elapsed days between the database lock or unblinding in the previous telaprevir study and Day 1 in this study