Hepatitis B Virus Nucleic Acid Amplification Testing Assay in Detecting Window Period and Occult Hepatitis B Virus Infections in Blood Donors

To reduce the residual risk of transfusion-transmitted infections, nucleic acid amplification testing (NAT) of donated blood with higher sensitivity for HBV, HCV, and HIV 1/2 was implemented in Bulgaria at the end of 2019. This study aimed to assess the clinical sensitivity of HBsAg testing and NAT testing of donated blood to detect all forms of HBV infection. A total of 9498 consecutive blood donations collected for six months, from February 10 to July 17, 2020, from first-time and repeat donors at the Regional Center of Transfusion Hematology Pleven, Bulgaria, were screened for HBsAg and HBV DNA. The detection of HBsAg was performed by enzyme-linked immunoassay and chemiluminescent immunoassay. Detection of HBV DNA was performed using the HIV1/2 /HCV / HBV multiplex Procleix Ultrio Elite assay in a fully automated and integrated Procleix Panther System. The overall HBsAg prevalence was 0.05%. HBV DNA was detected in 25 blood units (0.26%), but only 12 (0.13%) were found positive after repeat testing and were confirmed by a discriminatory test. The other 13 units were false positive, with the initial reactive result and negative results after repeat testing. HBV DNA’s overall incidence was significantly higher in HBsAg-positive donors than the HBsAg- negative (Fisher exact p=0.0063). In our study, blood donations were not tested for anti-HBc and anti-HBs, so it is difficult to determine whether HBV DNA-positive/HBsAg-negative results were associated with the early phase of infection or persistent occult infection. There was no statistical difference in the incidence of HBV DNA between repeat-donors (0.16%) and first-time donors (0.06%) (Fisher exact test p=0.239 NS), and also between the incidence in female donors (0.12%) and male donors (0.13%) (Fisher exact test p=1.0 NS). The results of this study showed a low rate of detection of the hepatitis B virus in donated blood. NAT testing demonstrates higher sensitivity for the detection of HBV, as compare to HBsAg screening.