Low Transmission Rate of Hepatitis E Virus by Transfusion of Hepatitis E Virus RNA-Positive Blood Products

Hepatitis E virus (HEV) can cause transfusion-transmitted (TT) infections. Therefore, in many countries, blood donor screening for HEV RNA has been established. The amount of infectious HEV RNA concentration in blood donations and screening strategy (pool size, single-sample testing) are still debated.

Blood donations, taken before the universal blood donor screening for HEV RNA, were investigated retrospectively for HEV RNA. Recipients of an HEV RNA-positive blood product were traced by look-back procedure. Archive samples of these recipients were investigated for TT-HEV infection by HEV RNA and anti-HEV IgG testing. HEV RNA concentration in the donor and in the transfused blood product was determined.

In 85/75,905 donations (0.1%), HEV RNA was detectable. A total of 28 recipients of 139 blood products from these donations could be further investigated. In 2/28 (7.1%) recipients, a possible TT-HEV infection occurred, but sequence analysis between donor and recipient could not be performed. HEV RNA concentration could be determined in 23 blood products and ranged from 10.9 IU/mL to 116,400 IU/mL donor plasma and absolute 120 IU-8,748,000 IU in the final blood product. In the cases of possible TT-HEV infection, HEV RNA concentration was 62,880 IU/mL donor plasma, according to 691,680-943,200 in the red blood cell concentrate and 593 IU/mL donor plasma, according to 8,302-11,267 IU in the pooled platelet concentrate.

Only a minority of HEV RNA-positive blood products caused a TT-HEV infection. With the limitation of the low number of investigated cases, even in blood products, which were contaminated with extremely high HEV RNA concentrations, there was no evidence for TT-HEV infection. Blood donor screening for HEV RNA by pooled samples should be favored over single-sample testing.