Immunological characterization of hepatitis B core antigen antibody among vaccinated adults lacking hepatitis B surface antigen in ethiopia: A multicenter facility-based study

Hepatitis B virus (HBV) infection remains a major public health challenge in Ethiopia, particularly among high-risk adult populations such as health professionals. Despite vaccination efforts, the prevalence and determinants of anti-hepatitis B core antibody (anti-HBc) seroreactivity among vaccinated adult health professionals lacking hepatitis B surface antigen (HBsAg) are not well characterized. Objective This study aimed to determine the prevalence and predictors of anti-HBc seroreactivity among HBsAg-negative vaccinated adult health professionals in hospitals of the northwestern region of Ethiopia. A facility-based cross-sectional study was conducted among 399 adult health professional who completed HBV vaccination series and were HBsAg negative from April to September 2024. Data on sociodemographic, clinical, and vaccine-related characteristics were collected via questionnaire. Serum samples were tested for HBsAg and anti-HBc using enzyme-linked immunosorbent assay (ELISA) kits at Debre Markos Blood Bank Laboratory. Data were analyzed using SPSS version 25. Bivariate and multivariate logistic regression analyses were performed to identify significant predictors of anti-HBc seroreactivity. In this study, the overall anti-HBc seroreactivity among HBsAg-negative vaccinated adult healthcare professionals was 25/399 (6.3%, 95% CI: 4.0%-9.0%). Participants born in rural areas had an anti-HBc seropositivity rate of 8.1%. Additionally, midwives exhibited a seropositivity rate of 11.7%. Among participants who had undergone organ transplantation, 66.7% showed anti-HBc seroreactivity. Moreover, among participants with a family history of liver disease, the prevalence of anti-HBc was 30.0%. Moreover, a previous history of chronic kidney disease (AOR: 9.1, 95% CI: 7.56–11.98, P < 0.014) and obesity (AOR: 6.9, 95% CI: 4.91–8.63, P < 0.003) were significant predictors of anti-HBc seroreactivity. Anti-HBc seroprevalence among HBsAg-negative vaccinated adult healthcare professionals was notable. This finding underscores the critical need for post-vaccination testing to identify HBV infections.