Abstract: Objective The aim of this study was to investigate the prevalence of occult hepatitis B viral infections (OBI) in blood donors (BD). Methods 107397 blood samples were collected in our Blood Station between January and December 2021. The initial serum screening of HBsAg was conducted by two ELISA kits, and serum HBV DNA loads was assayed by NAT. For serum HBV DNA positive samples, serum HBV markers were repeatedly detected and HBV genotype was determined by real-time fluorescence quantitative polymerase chain reaction (PCR). Results Out of the 107397 blood samples, the OBI was found in 29 cases (0.27‰) as defined by serum HBV DNA positive; the re-testing of the positive blood showed that serum anti-HBc positive in 12 cases (35.3%), anti-HBe/anti-HBc positive in 8 cases (23.5%), anti-HBs/anti-HBc positive in 6 cases (17.7%) and anti-HBs/anti-HBe/anti-HBc positive in 3 cases (8.8%); the prevalence of OBI in individuals at 19-29 year old was 0.09‰, in those at 30-39 was 0.32‰, in at 40-49 was 0.39‰ and in at 50-55 was 0.41‰, and in persons at age of 50-55 with more than one time blood donor, the prevalence of OBI was 0.31‰; the percentages of serum HBV DNA loads greater than 1000 IU/mL in OBI individuals with serum anti-HBs/anti-HBc positive and with serum anti-HBs/anti-HBe/anti-HBc positive were 33.3% and 66.7%, significantly higher than 0.0% in those with serum anti-HBc positive (P<0.05) or with serum anti-HBe/anti-HBc positive (0.0%, P<0.05); out of the 29 OBI persons, the genotype C infection accounted for 62.1% and genotype B infection for 27.6%. Conclusion The prevalence of OBI in blood donors is a challenge for public health security, and the cost-efficacy of all-scale detection of serum HBV DNA loads in this setting needs further investigation. The quality and sensitivity of conventional ELISA kits should be improved.

Key words: Occult hepatitis B virus infection, Hepatitis B surface antigen, Enzyme-linked immunosorbent assay, Nucleic acid test, Blood donors