Since 1 January 2020, testing of all blood donors for hepatitis E virus (HEV) RNA is mandatory in Germany. However, this measure is not without controversy. Other countries have decided against routine screening [1, 2]. To estimate the benefit of this measure, the rate of HEV transmission through blood products before the introduction of mandatory testing was investigated
retrospectively in our institution.

All blood donations given between 26 May 2017 and 31 December 2018 were retrospectively tested for HEV RNA by NAT (cobas HEV, Roche Diagnostics, Mannheim, Germany) in minipools up to 48 samples.
After resolution of reactive minipools recipients of the HEV RNA-positive blood products were identified. For some recipients, archive samples that have been collected at the day of transfusion and additional samples collected thereafter, were available for follow-up. Whether a transmission of HEV by transfusion has occurred, was investigated by ID-NAT-testing as well as antibody testing of the recipients archive samples (HEV ELISA IgG, EUROIMMUN, Lübeck, Germany).
Clinical courses in HEV-infected patients were assessed by medical records.

75,905 blood donations were given by 23,703 donors. 85 HEV RNA positive donations from 76 donors were identified. This represents 0.12% of all blood donations and 0.32% of donors. 139 HEV RNA-positive blood products were transfused. From 30 recipients archive samples were available for further analysis. In 3/30 (10 %) patients, IgG-antibodies were detectable already before transfusion.
IgG antibodies were detected in 6/27 (22,2 %) other recipients, in four recipients of red blood cell (RBC) concentrates and in two recipients of platelet concentrates. HEV RNA was detected in only one of these recipients 55 days after transfusion of a RBC. She had no other laboratory or clinical signs of hepatitis, the clinical course was uneventful.

In six of the HEV antibody-negative patients, HEV-IgG antibodies could be detected after transfusion, in five of them passive antibody transfer might explain this finding. In only 1/27 (3.7
%) presumably susceptible patient, HEV RNA was detectable after transfusion of an HEV RNA-positive RBC. The transmission rate of HEV by transfusion was lower than expected based on the data available [3]. It may therefore be reasonable to reassess the cost-benefit ratio of HEV RNA-testing in blood donors.

There is no conflict of interest.