HBsAg confirmatory test

[armymt2002]

When a confirmatory test result for a donor is reported as non-confirming what exaclty does it mean. Thanks.

[David Saikin]

This means that whatever is causing the reactivity in the HBsAg assay is not neutralized by the HBsAb in the confirmatory assay. This then interprets that the individual is not reactive for HBsAg, but for some other moiety which is reacting with the Sag assay. The assay performed is a screening assay and must be confirmed by a method specific to the assay being performed. The 2 assays I am familiar with use HBsAb to neutralize the HBsAg - if it is neutralized then this confirms the presence of HBsAg. Hope this is not too confusing. . .

[DFields]

Does anyone have a letter example which they send to a donor whose sample cannot be found either neg or pos for HBsAg? Are those donors kept ('forever') on a permanent deferral since the sample is non-confirming?

[jralston]

Non-confirming would mean either that when the HBsAg positive donor sample was sent for confirmatory testing, it was not not neutralized (not-confirmed) or the confirmatory test used was not an actual confirmatory test, but possibly a supplemental test. General I would think that non-confirmed means just that, the confirmatory test did not confirm HBV.

[detective343]

Can anyoone confirm what is meant by:

weak hbsag reactivity. And would weak reactivity imply that the hbsag is in low titre?

Many thanks if you can.