What is your approach to determining the need for continued isolation in the dialysis unit for an ESKD patient who had a positive hepatitis B surface antigen one year ago but who now has a negative HbsAg in the absence of treatment?

I have not encountered this situation before. Assuming that both checks are accurate and not the result of vaccination, then I would continue to isolate for another 6 months, repeat Hep BsAg and viral load. If still negative would take off isolation.