Characteristics of occult hepatitis B infection among pregnant women in the Center Region of Cameroon: rationale for universal administration of hepatitis B birth dose vaccine

Occult hepatitis B infection (OBI) among pregnant women poses a significant public health problem in the prevention of vertical transmission. A seroprevalence of overt hepatitis B among pregnant women in the Centre Region of Cameroon of 6.8% was reported. Although data on OBI is scarce among pregnant women in Cameroon, 5.5% was reported in AIDS patients in the Centre Region. The aim of this study was to determine hepatitis B virus (HBV) molecular and serological characteristics in OBI among pregnant women and to inform and guide policy makers in the development of prevention strategies of vertical transmission of HBV. A cross-sectional, descriptive study was conducted from January 2022 to July 2024 among pregnant women attending antenatal care centers in seven health facilities in the Centre Region of Cameroon. Venous blood was collected from women who gave written informed consent, and tested for HBsAg and anti-HIV antibodies using rapid tests and ELISA. Samples that were negative for HBsAg were further tested for HBeAg, anti-HBs and anti-HBc antibodies using ELISA. Plasma HBV DNA presence was detected and measured by nested PCR and real-time PCR, respectively, while HBV Sanger sequencing was performed on the HBV S gene, and a phylogenetic analysis using the MEGA software. Of 2033 HBsAg-negatives, HBV-DNA was tested in 249 (75 HIV-infected and 174 HIV-negative selected randomly). The rate of 3 dose hepatitis B vaccination in the study population was 7.2% (18/249). Of the 75 HIV-positive cases, 9.6% (24/75) and 12.1% (30/75) were positive for anti-HBs and anti-HBc antibodies, respectively. HBV-DNA was detected in 3.6% (9/249) and these were not vaccinated. The prevalence in the nine OBI cases were 77.8% (7/9), 55.6% (5/9), and 22.2% (2/9) for anti-HBc, anti-HBs, and anti-HBe antibodies, respectively. HBV genotypes A and E were identified in 2 cases each, and sY100C and sM125T mutations in 3 of the 4 cases. The prevalence of OBI among pregnant women highlights the need to promote hepatitis B birth dose vaccination for all newborn and not only for the exposed, as in the case of some African countries.