Serological Evidence of Hepatitis B Virus Core Antibody Among Fully Vaccinated Infants in Cameroon: Implications for Perinatal Exposure and Vaccine Response

The hepatitis B virus (HBV) remains highly endemic in Sub-Saharan Africa, where perinatal and early childhood transmission contribute substantially to chronic infection. Although routine infant vaccination is widely implemented, the birth-dose coverage remains inconsistent in many settings. This study, carried out in strict compliance with ethical rules, evaluated serological markers of HBV exposure and vaccine-induced immunity among fully vaccinated infants in Cameroon. It was a cross-sectional study involving 9-to-15-month-old infants, fully vaccinated against hepatitis B and HIV negative, living in the towns of Douala and Yaoundé. Infants born to mothers known to be HBsAg-positive were excluded. Their serum samples were tested for HBV serological markers, using lateral flow immunochromatography techniques and indirect ELISA. Whereas 84.85% (56/66) of theses infants achieved seroprotective antiHBs levels, 16.67% (11/66) were antiHBc-seropositive and were all born to antiHBc-seropositive mothers. Overall, 63.64% of these antiHBc-seropositive infants were significantly less likely to demonstrate seroprotection compared with antiHBc-seronegative infants (adjusted OR 30.3; 95% CI 5.58–164.75). These results, highlighting the association between antiHBc positivity and reduced seroprotection, warrant further investigation, including molecular testing to distinguish passive maternal antibody transfer from occult or resolved infection. Strengthening perinatal HBV prevention strategies remains critical to achieving elimination targets.