Background: To understand the risk of transfusion-transmitted viral infection, it is important to precisely assess cases of infection that follow transfusion.
Study design and methods: HBV infections noted after transfusion in 1997, 1998, and 1999 were analyzed. Transfusion in all these cases was performed before NAT was adopted for donor screening. To detect viral infection, PCR and serologic tests for HBV were performed retrospectively on all blood samples from implicated donors that had been stored in a frozen state after each donation. The concentration of HBV genome was measured in HBV-positive blood samples.
Results: One hundred three cases of HBV infection were analyzed; of these, only 16, including at least 10 infections due to window-period (HBsAg-positive by reverse particle hemagglutination assay) donations, were confirmed by further testing to be related to transfusion. The concentrations of HBV genome were very low in four blood samples (<50, 400, 500, and 800 genome equivalents/mL of plasma).
Conclusions: The remaining risk of transfusion transmission of HBV infection before the adoption of NAT was mainly due to window-period donations, including one that was made before the HBV genome was detectable by PCR. However, it was determined that transfusion was not responsible in many cases for HBV infection after transfusion.