Universal nucleic acid donor screening revealed epidemiological features of hepatitis E and prevented transfusion‐transmitted infection in Japan

Abstract

AbstractBackgroundMore than 45 cases of transfusion‐transmitted hepatitis E virus infection (TT‐HEV) have been reported in Japan. Therefore, in 2020, universal individual donation nucleic acid amplification testing (ID‐NAT) was implemented for HEV.Study Design and MethodsWe characterized HEV NAT‐positive blood donors. The number of new HEV infections and the asymptomatic infection rate were estimated using the HEV NAT‐positive rate. HEV RNA quantitation, phylogenetic analysis, and antibody tests were performed, and the residual risk of TT‐HEV was assessed based on the lookback study results.ResultsA total of 5,075,100 blood donations were screened with ID‐NAT during the first year of implementation, among which 2804 (0.055%; males: 0.060%, females: 0.043%) were NAT‐positive with regional differences. Approximately 270,000 new HEV infection cases were estimated to occur annually in Japan, with an asymptomatic infection rate of 99.9%. The median HEV RNA concentration, excluding cases below the limit of quantification, was 205 IU/mL. Among the 1113 cases where the genotype could be determined, HEV‐3 and HEV‐4 accounted for 98.8% (1100) and 1.2% (13), respectively. The maximum duration of HEV viremia, including the pre‐ and post‐ID‐NAT window periods, was estimated to be 88.2 days. Within the 3 years since ID‐NAT implementation, no confirmed cases of breakthrough TT‐HEV were observed.DiscussionMultiple indigenous HEV strains are prevalent in Japan, infecting a significant number of individuals. However, since the implementation of ID‐NAT, TT‐HEV has been prevented due to the test's high sensitivity.