Background

Testing for HEV RNA has been mandatory for all medical products by the Paul-Ehrlich Institute (PEI) since 2019. Since 2020, Haema AG also tests all source plasma donations. It is shown that low HEV RNA concentrations in plasma pools have been detected [1] and no transmission of HEV RNA through plasma derived medicinal products has been reported to date [2]. Dreier et al. estimated a general infectious dose of 50,000 IU/ml and 7,050 IU/ml as a minimum dose [3].

Methods

From 2021 to 2022, we have analyzed over 2.24 million donations for HEV RNA in Germany to PEI specifications, the test method used for the HEV-NAT must reliably detect a HEV RNA concentration of 2,000 IU/ml based on a single blood donation for medicinal products. Therefore, HEV RNA was tested in a pool of 96 samples – also for plasma donations. We used the Roche cobas 6800® with the PCR method (Polymerase Chain Reaction) and a sensitivity of 18.6 IU/ml (ID-NAT) and the Grifols Procleix Panther with the TMA method (Transcription-Mediated Amplification) and a sensitivity of 7.89 IU/ml (ID-NAT). We determined the virus concentration for one quarter (semiquantitative) by using a standard curve for HEV RNA.

Results

Since the start of HEV testing, the number of HEV positive donations has continually increased from 203 donations in 2021 up to 424 donations in 2022 to 127 donations in the first quarter of 2023 (Tab.1). We detect most of the HEV positive donations from plasma donors (78.3%), as most donors are repeated donors and are therefore tested frequently. 54% of the HEV RNA positive plasma donations had a low virus viral load (50 to 500 IU/ml), 42% had a viral load in the range of 500 to 50,000 IU/ml and 4% of the donors were detected with a viral load >50,000 IU/ml (Tab.2). The low viral load in a large number of donations could assume that more early-stage infections are detected.

Conclusion

According to the PEI, an 80% risk reduction was achieved by using a 96 pool with an analytical sensitivity of 20 IU/ml. Based on this, not all infections could be detected particularly in the early stage of infection. Blood donors had a significantly lower virus load than symptomatic patients [4]. Due to the increasing number of HEV positive donors, viral load might become more important.

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Literature: (1) Baylis SA et al. Transfusion.2016;56:2532-2537 (2) Kapsch A et al. Transfusion.2020;60:2500-2507 (3) Dreier et al. Front Med 2018 (4) Lhomme et al. J Viral Hepat. 2019 Sep;26(9):1139-1142