Hepatitis B and D: a forecast on actions needed to reduce incidence and achieve elimination

BackgroundViral hepatitis negatively affects the health of millions, with the worst health outcomes associated with the hepatitis D virus (HDV). Fortunately, HDV is rare and requires prior infection with the hepatitis B virus (HBV) before it can establish infection and transmit. As such, public health officials have opted to indirectly control HDV by reducing HBV incidence, primarily through hepatitis B vaccination, which has dramatically reduced HBV incidence since its rollout in the 1980s. However, investigations into the consequences of hepatitis B vaccination on both the control and evolution of HDV remain limited. MethodsWe developed a mathematical model of HBV and HDV transmission to investigate the effects of hepatitis B vaccination on both HBV and HDV. We calibrated our model to the HBV and HDV transmission scenarios occurring in Sub-Saharan Africa, and estimate HBV vaccination thresholds that cause HBV and HDV elimination, inhibit the spread of virulent HDV strains, and achieve the targets set by public health authorities for reducing all viral hepatitis incidence by 90%. ResultsOur findings illustrate hepatitis B vaccination rates above 0.0096 year-1 and 0.018 year-1 will likely achieve HDV and HBV elimination, respectively. Furthermore, in the majority of transmission settings, scaling-up vaccination rates to at least 0.009 year-1 or 0.02136 year-1 will achieve the 90% reduction in hepatitis D and B, respectively, called for by health authorities. ConclusionOur results suggest a scale-up of hepatitis B vaccination is required to achieve the targets set by public health officials for reducing all viral hepatitis by 90%. Furthermore, the scale-up required to achieve such targets would bring HBV and HDV to the brink of the vaccination threshold required for their elimination. Thus, with sufficient investments to scale up global hepatitis vaccination, prevention, testing, and treatment services, the eradication of both HBV and HDV are likely feasible endeavors, especially once the 90% reduction goal is reached.