PPIB and Hepatitis: In addition to factors such as HBsAg prevalence and the speed and final levels of vaccination scale-up, taking the aforementioned characteristics (risk of vertical transmission, fertility of older women, dominance of older age groups in the population) into account may explain why some of the countries in de Villiers et al. (2021) may take several decades to reach hepatitis B elimination if vaccination rates do not increase in the future.