Anti-HBs levels after hepatitis B immunisation depend on test reagents: routinely determined 10 and 100 IU/l seroprotection levels unreliable.

In a large series of post-vaccination samples we compared the result of three commercially available anti-HBs assays (AxSYM, Architect and Access) on the quantitation of anti-HBs after immunisation with Engerix-B (HBsAg/ad) and GenHevacB (HBsAg/ay) vaccine. Two of the assays (AxSYM, Architect: Abbott Laboratories) gave related but not identical results with HBsAg from different sources. The result of the third assay (Access, Beckman Coulter) was related to that of AxSYM and Architect only for GenHevacB anti-HBs but differed for Engerix-B anti-HBs (P<0.001). This vaccine dependent discrepancy was also observed with the Vidas anti-HBs assay (BioMerieux). An external WHO reference panel could harmonise geometric mean anti-HBs levels from the four assays for GenHevacB but not for Engerix-B vaccination sera. We conclude that the individually determined anti-HBs level (IU/l) strongly depend on the test reagents and the vaccine under study.