SaBTO Working Group Assesses Effectiveness of Current HEV Screening

The Hepatitis E Virus (HEV) Working Group of the United Kingdom’s Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) published a review this week assessing the effectiveness of the country’s current HEV screening strategy. The review follows the death of an immunocompromised patient who became infected with HEV following a platelet transfusion. The donation contained enough virus to cause infection but remained below the threshold detectable by current screening methods.

In its review, the working group found that existing screening, which uses pooled nucleic acid testing for all blood and apheresis platelet donations, remains effective. The group estimated that only a tiny fraction of donations, around 0.004% of apheresis donations and 0.003% of whole blood donations, would have undetected HEV each year. The predicted infectivity of blood components depended on their residual plasma content, ranging from 33% for apheresis platelets to 4% for red blood cells.

The working group also reviewed options to further reduce HEV transmission risk. The report noted that testing individual donations could almost eliminate residual HEV infections but would cost roughly 11 million pounds, more than 60 times the calculated health economic benefit (176,000 pounds). The report also noted the potential use of platelet additive solution to reduce residual plasma volume in platelets.

While the working group did not recommend any change to the current HEV screening practices, the report includes additional recommendations. These focus on evaluating risk tolerability in HEV screening, raising clinician awareness of HEV infection and monitoring HEV incidence in the wider community. Significant increases in HEV cases should prompt U.K. blood services to re-evaluate testing strategies, the working group said.

Furthermore, the group recommended that a review of how changes in key factors could affect the report’s findings should take place in five years. Potential factors for review include progress in HEV control in pork production, advances in testing methods and blood safety technologies, and improvements in clinical understanding and treatment of HEV infections.