Hepatitis B virus (HBV) infection remains a significant global health concern worldwide, contributing to high rates of mortality and morbidity, including chronic hepatitis B, cirrhosis, and hepatocellular carcinoma (HCC). Universal vaccination programs have significantly reduced the rate of HBV transmission; however, a subset of individuals fail to develop a protective immune response following vaccination and are termed nonresponders. A comprehensive search strategy using the PubMed, Google Scholar, and Web of Science databases was employed to search for relevant studies using keywords including “hepatitis B vaccine”, “vaccine nonresponse”, “immunogenicity”, “immune response to the hepatitis B vaccine”, and “associated risk factors”. Factors influencing the vaccine’s response include demographic factors, such as age and sex, with increased nonresponse rates being observed in older adults and males. Obesity, smoking, and alcohol consumption are lifestyle factors that decrease the vaccine response. Medical conditions, including diabetes, chronic kidney and liver diseases, HIV, celiac disease, and inflammatory bowel disease, affect the vaccine response. Major histocompatibility complex (MHC) haplotypes and genetic polymorphisms linked to immune regulation are genetic factors that further influence the vaccine’s effectiveness. To reduce the global burden of hepatitis B infection, it is essential to understand these factors to improve vaccine effectiveness and develop individualized vaccination strategies.

Background: Hepatitis B virus (HBV) remains a significant global health concern, particularly in sub-Saharan Africa, where endemicity is high. Occult hepatitis B infection (OBI) presents a unique challenge to transfusion safety, as HBV DNA may persist in HBsAg-negative individuals. This study examines the prevalence of HBcAb positivity among blood donors at Usmanu Danfodiyo University Teaching Hospital (UDUTH), Sokoto, and assesses the risk of HBV transmission. Methods: A cross-sectional study was conducted among 200 blood donors. Samples were screened for HBsAg and HBV serological markers using a rapid assay and ELISA. HBcAb-positive samples were analyzed for HBV DNA using real-time polymerase chain reaction (qRT-PCR). Viral loads were quantified, and socio-demographic characteristics were recorded. Results: HBcAb was detected in 57 (28.5%) of the 200 donors. The most common serological pattern among donors was HBsAg-negative and HBcAb-negative (69%). Among these HBcAb-positive donors, HBV DNA was detected in three cases (1.5%), with viral loads of 753.1, 2.193 × 10⁴, and 4.538 × 10⁴ IU/mL. The presence of HBV DNA in these donors confirms the risk of OBI transmission through transfusion. Socio-demographic analysis revealed that 48.5% of donors were aged 26–35 years, 23.5% were aged 18–25 years, 23% were aged 36–42 years, and 2.5% were either 43–50 or above 50 years of age, of which 99.5% were male. These findings highlight a significant prevalence of HBcAb positivity and OBI, aligning with studies in similar high-endemic settings. Conclusions: HBcAb positivity and OBI represent significant transfusion risks in endemic regions. The presence of HBV DNA in 1.5% of HBcAb-positive donors in the study population highlights the limitations of HBsAg-based screening. Incorporating nucleic acid testing (NAT) into routine blood donor screening protocols is critical to enhancing transfusion safety. Further research is needed to evaluate the feasibility and cost-effectiveness of such interventions in resource-limited settings.