Heplisav-B Revaccination for Hepatitis B Vaccine Nonresponders

Inclusion Criteria: * Age \>18 by age of screening * If HIV positive, either: * Suppressed on a stable, ARV regimen for \>4 weeks with CD4 count \>100. HIV VL suppressed \<50 copies/mL, although single isolated VL \>50 not excluded. OR * Untreated ≥ 8 weeks with CD4 count \>100 * Prior HBV vaccine (other than Heplisav) with last dose \>30 days prior to screening and anti-HBSAg ≤10 IU/mL measured \>30days from last vaccine dose. (No exclusion for HBV CAb positive.) * Ability to provide informed consent and adhere to clinic visits (in the judgment of both the participant and the provider) * No history of adverse reaction to HBV vaccines or components thereof * If HCV Ab positive: undetectable HCV viral load and \>12 weeks from completion of any HCV therapy. Exclusion Criteria: * History of allergic reaction to HBV vaccines or components (including yeast) * HBsAb titer \>10 IU/mL on screening evaluation * Clinically significant illness (other than HIV) that may, in the opinion of the investigator, interfere with the subject treatment, or adherence to protocol. This may include but is not limited to a history of transplant, decompensated cirrhosis, or malignancy that may interfere with host immunity. * Poor venous access interfering with blood sample collection * Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer's…