BACKGROUND
Because anti-hepatitis B core antibody testing is not obligatory, blood donors with occult hepatitis B infection (OBI) may transmit hepatitis B virus (HBV) to a recipient despite the use of nucleic acid amplification technology (NAT) or pathogen inactivation (PI).
STUDY DESIGN AND METHODS
We developed a model to estimate OBI transmission risk based on three components: 1) the probability distribution of the viral load (VL) in a randomly selected OBI donor, 2) the probability that a given VL remains undetected, and 3) the probability that this VL causes infection in the recipient. A subset of 217 South African OBI samples identified by individual donation (ID)-NAT screening were quantified by replicate testing using an ID-NAT assay (Ultrio Plus) against HBV DNA standard dilution series. The observed log VLs could be described by a Gumbel distribution. A correction was included to compensate for OBI samples missed by initial ID-NAT screening.
RESULTS
The model estimates that 3.3% of all OBI donations are undetected by ID-NAT (Ultrio Plus) and cause infection by a blood component containing 20 mL plasma, going up to 8.7% when using minipools of 6 (MP6)-NAT. For 200-mL plasma transfusion these risks were estimated at 14 and 28%, respectively, while PI with modest (2 log) reduction capacity would reach 4.8% without NAT and 1.3 or 0.4% when combined with MP6- or ID-NAT.
CONCLUSION
The model can be used to compare different screening and/or PI strategies in reducing viral transmission risk and could serve as a tool in evaluating efficacy of alternative blood safety scenarios.
Transfusion. 2017 Mar;57(3pt2):841-849. doi: 10.1111/trf.14050. Epub 2017 Feb 28.
A mathematical model for estimating residual transmission risk of occult hepatitis B virus infection with different blood safety scenarios.
Weusten J1, van Drimmelen H2, Vermeulen M3, Lelie N2,4.