An ultra-sensitive Abbott ARCHITECT ® assay for the detection of hepatitis B virus surface antigen (HBsAg).

•A new Abbott ARCHITECT® HBsAg assay was developed to improve sensitivity.•Analytical sensitivity was improved to 5.2 mIU/ml.•Enhanced sensitivity was demonstrated with seroconversion and NAT-yield samples.•Detected all mutants and genotypes with higher sensitivity than comparator assays.•Assay specificity was not diminished, attaining 100% on 10,633 blood donors.