Hepatitis B surface antigenaemia following vaccination with a combined vaccine against hepatitis A and B.

We report a case of transient hepatitis B surface antigenaemia (HBsAg) following vaccination with a combined vaccine against hepatitis A and B in healthy adults. This phenomenon has been observed following administration of recombinant hepatitis B (monovalent) vaccine, mainly in newborns or dialysis patients. Reports on healthy adults are much less frequent and mostly concern blood donors. The frequency of its occurrence is largely unknown but its duration does not exceed 28 days. It is not detected by all available assays. It is caused by a passive transfer of antigen by vaccination, and not by viral replication; hence there is no risk for vaccination-induced infection. An important implication resulting from our findings is that the results of HBsAg assays should be interpreted according to the time elapsed since the last administration of a recombinant monovalent vaccine against hepatitis B or a combined vaccine against hepatitis A and B.