Performance evaluation of the re-standardized Abbott Architect anti-HBs assay

As defined by World Health Organization (WHO), an antibody level of ≥ 10mIU/mL to hepatitis B virus confers protection. With the launching of Abbott anti-HBs assay re-standardized to the 2^nd WHO International Reference Preparation, a positive bias in antibody level would be anticipated. Manufacturer provides limited data for samples around the immune cut-off which has potential implication on vaccine guidance.

To evaluate the performance of the re-standardized Abbott Architect anti-HBs assay and to determine the impact of the upward shift.

A total of 52 samples, including 12 external quality assurance programme samples and 40 clinical samples were tested with both the Abbott 1^st WHO standardized and the 2^nd WHO re-standardized assay and results compared. The 2^nd WHO anti-HBs standard and Acometrix anti-HBs control were also included for comparison.

Verification of the re-standardized assay with the 2^nd WHO anti-HBs standard revealed positive bias with mean closer to target value. Overall, the positive bias introduced by the new assay will only affect interpretation of samples with anti-HBs levels > 5.00 to < 10.00 mIU/mL previously tested on the Abbott 1^st WHO standardized anti-HBs assay.

Final interpretation of immune status to hepatitis B was not affected by the upward shift following introduction of the new Abbott anti-HBs assay except for previously negative samples with anti-HBs levels between >5.00 to <10.00 mIU/mL.