Liverpool researchers have conducted a large-scale analysis that sheds light on the critical steps needed to combat the vertical transmission of chronic hepatitis B virus (HBV) in Africa.
Almost two thirds of all new hepatitis B infections globally occur in Africa. The newly published paper in The Lancet Global Health shows the importance of giving the hepatitis B birth dose vaccine (HepB-BD) within 24 hours of birth, and the potential impact of providing antiviral therapy (antiviral prophylaxis) to mothers during pregnancy. The study estimates for the first time that hepatitis B vertical transmission (passed from mother to baby) could be eliminated in Africa, with increased coverage of these two key interventions.
Chronic hepatitis B is the leading cause of liver cancer and liver cirrhosis in Africa and deaths are rising. Most cases of liver cancer are diagnosed late and are associated with a very poor prognosis in the region. Vertical transmission is one of the commonest routes of infection and is associated with an increased lifetime risk of severe liver disease.
Dr Alexander Stockdale, Senior Clinical Lecturer at the University of Liverpool's Department of Clinical Infection, Microbiology and Immunology, based at the Malawi-Liverpool-Wellcome Trust Clinical Research Programme, together with Dr Nicholas Riches at Liverpool School of Tropical Medicine, led the comprehensive analysis of more than 113 individual studies which reported on the prevalence of hepatitis B in more than 190,000 women and investigated rates of vertical transmission.
The World Health Organization (WHO) African region faces a significant burden, accounting for 63% of the global total of new infections. This amounted to 771,000 new infections and 272,000 deaths in 2022. Among children under 5 years, the prevalence of HBV stands at 2.5% in the WHO African region - the highest globally.
Dr Stockdale said: “This study makes the case for investment in birth dose vaccination and maternal antiviral prophylaxis, in view of the exciting potential for elimination of vertical transmission in the WHO African region in our lifetime. Vertical transmission is a key route of new hepatitis B infections. Due to limited implementation of interventions, elimination targets are not currently being met. We project that expanding HepB-BD vaccination coverage to 90% could reduce transmission events by 44%, and adding maternal antiviral prophylaxis for 90% of eligible women could further reduce transmission by 86% and achieve the WHO targets for elimination.”
Dr Stockdale and colleagues have also recently been awarded £3million funding from the National Institute of Health and Care Research to conduct implementation research in Malawi and The Gambia. The NIHR Global Health Research Grant will allow researchers in Malawi, led by Dr Stockdale and in The Gambia, led by Professor Maud Lemoine and Dr Gibril Ndow, to evaluate the effectiveness, safety, feasibility and cost-effectiveness of giving antiviral treatment (tenofovir) to all pregnant women living with chronic hepatitis B to prevent transmission. This study will provide vital evidence on the potential impact of this strategy to guide public health policy in Africa, which has been recognised as a key knowledge gap by the WHO in the 2024 hepatitis B guidelines.