A revised method for estimating hepatitis B virus transfusion residual risk based on antibody to hepatitis B core antigen incident cases.

Background: To take into account the transient nature of hepatitis B virus (HBV) antigenemia, the calculation of HBV residual risk (RR), based on the incidence/window period model, is adjusted by a correction factor that adds uncertainty to the RR estimates.

Study Design And Methods: This new method to estimate the RR for HBV is a weighted sum of the RR derived from hepatitis B surface antigen (HBsAg) incident cases and the one derived from antibody hepatitis B core antigen (HBc) incident cases. An anti-HBc incident case was defined as a donation from a blood donor who had made at least one anti-HBc-negative donation followed by a donation that was found positive with two different assays within a 3-year period and positive for at least one of the following markers: 1) antibody to hepatitis B e antigen or hepatitis B e antigen, 2) anti-HBc immunoglobulin M, 3) HBV DNA, 4) hepatitis B surface antibody without HBV vaccination history, or 5) HBV DNA retrospectively found in the previous donation.

Group o human immunodeficiency virus type 1 infection that escaped detection in two immmunoassays.

We report a case of human immunodeficiency virus type 1 group O infection not detected by two highly sensitive immunoassays. The sera were strongly reactive to the V3 peptide of group O but not to the gp41 immunodominant epitope. Gp41 was sequenced, confirming that this virus belonged to group O.