This is a long term follow-up study for chronic hepatitis B (CHB) subjects who have received imdusiran treatment in a prior clinical trial, stopped NA therapy during that trial, and remain off therapy. Subjects may enroll after completing the end of study visit (baseline visit within 12 weeks ± 1 week from the end of study [EOS] visit) from their imdusiran clinical trial (the "parent study"). No interventions will be performed in this study other than blood sample collections, review of current medications, and reporting of any adverse events related to study procedures or NA therapy if restarted. Study participation will be for approximately 2 years (to complete a total of at least 3 years of follow-up while off NA therapy, inclusive of parent study participation).

Key Inclusion Criteria:

• Have participated in a prior imdusiran clinical trial,
• Have discontinued NA therapy in that trial and remain off NA therapy,
• Have completed less than 3 years of follow-up visits after NA discontinuation in the parent study.
• Have the ability to review and provide signed informed consent which includes compliance with all protocol-specified visit schedules and requirements.

Exclusion Criteria:

• Not applicable

CHB subjects who have received imdusiran treatment in a prior clinical trial, stopped NA therapy during that trial, and remain off therapy at the end of study visit.