OA1-AM24-ST-06 - A Haemovigilance Perspective on Routine HEV-RNA NAT Testing in Swiss Donors

Routine HEV-RNA NAT testing was introduced in Switzerland on October 2018. Patient and donor look-back procedures were implemented as part of haemovigilance monitoring. Since 2018, more than 1.4 million donations were tested for HEV infection; one probable case of transfusion-transmitted infection (TTI) was observed by a patient look-back procedure in 2018. 

Study

Design/Methods: Routine donor HEV-RNA NAT testing is performed with a maximum of 24 donations per pool using Roche Diagnostics (cobas6800/cobas8800) or Grifols (Panther) reagents. A minimum 450 IU/mL single donation detection limit is required. For look-back procedures, an individual HEV-RNA NAT test is performed on archived samples. Blood components obtained from previous donations within the defined observation period are discarded. The observation period for donor look-back was reduced in 2021 from 6 to 3 months, after evaluation of surveillance data and considering that viremia usually lasts a maximum of two months. Patient look-back is triggered when a recipient of blood products is suspected to have HEV TTI.

Results/Findings:

Of the 1 404 418 donations tested between 2018 and 2023, 300 positive HEV donations were detected, of which 36 were first time donors and 264 regular donors (Table 1). 77 donor look-back (DLB) procedures were performed: 8 in 2018, 36 in 2019, 18 in 2020, 10 in 2021, one in 2022 and 4 in 2023. Since 2018, no confirmed TTI has been detected by donor look-back studies. However, in 2018, three patient look-back (PLB) procedures were carried out. In two cases no correlation was found with the donation. In one case, a correlation could not be excluded; and it was agreed not to perform this costly look-back procedure as the patient with hepatitis E was successfully treated and the added value of changing a probable case into an eventual "certain" case was mainly statistical. No other PLB procedures were carried out in the following years.
An increase in HEV-positive donations was observed in 2019 and in 2021. Regional outbreaks in blood donors have already been described in the literature (Fontana et al., Microorganisms, 2023). In 2021, however, this increase was correlated with an outbreak observed in the general population, suggesting food as a potential infection reservoir (BAG-Bulletin, 4/22).

Conclusions:

The introduction of the HEV NAT test prevented the transfusion of 300 contaminated blood products between 2018 and 2023. Since 2018, no donor look-back procedure revealed any TTI. Only one probable transmission was observed in a patient look-back in 2018. The routine HEV-RNA NAT in minipools is considered a valuable safety measure.