Blood HBV DNA in newborns from HBsAg-positive mothers might be predictive of immunization response

Background: In Ivory Coast, as in the rest of sub Saharan Africa, despite the introduction of anti-hepatitis B vaccine, toddlers and children remain a segment of the population frequently infected with Hepatitis B Virus (HBV). The conditions of early HBV transmission, and notably the materno-fetal route remain summarily documented in sub Saharan Africa. Methods: From June to November 2018, we analyzed the socio-demographical, serological, and viral features related to HBV transmission in expectant mothers and their newborns who came for delivery at the CHU Cocody Abidjan. Results: Out of 1628 contacted expectant mothers, a subset of 508 accepted to participate to the study, including 163 who were positive for HBsAg. All 56 mothers who transmitted either HBsAg or HBV DNA to their babies were presenting HBV DNA loads >5.0 log10 IU/mL Remarkably, fates of newborns either positive for HBsAg or HBV DNA who completed immune-prophylaxis were drastically different at 9-12 months. While a majority (90%) of HBsAg (+)-only babies became anti-HBs (+), 62.5% DNA-positive newborns failed to mount a proper anti-HBs response. Overall, 10.7% of newborns with at least one positive HBV marker at birth develop a bona fide chronic infection at 9 months. Conclusions: In Ivory Coast, pregnant women presenting HBV DNA loads above 5.0Log10 IU/mL are at risk of maternofetal transmission. Presence of HBV DNA in the blood of newborns represents a better predictor of anti-HBV immunization failure than HBsAg presence. An adaptation of immunization procedures with a passive immune prophylaxis targeting specifically newborns at risk should be urgently considered.