Impact of hepatitis B virus immunization

Abstract

Hepatitis B virus (HBV) infection remains a global public health issue due to its potential for chronicity and severe complications such as cirrhosis and hepatocellular carcinoma. Since its introduction in the 1980s, vaccination against HBV has proven to be a highly effective tool in preventing acute infection, chronic disease, and vertical transmission. This article reviews the impact of hepatitis B vaccination globally and in Spain, based on data from epidemiological surveillance, seroprevalence studies, and cancer registries. Remarkable reductions in the incidence of chronic infection and hepatocellular carcinoma have been observed in countries that implemented the vaccine early, such as Taiwan, China, and Iran. In Spain, vaccination began in risk groups in 1982, was extended to adolescents in the 1990s, and to infants from 2002. Vaccination coverage has exceeded 93% in infants for over two decades. The incidence of acute hepatitis B has decreased significantly since 1997, and seroepidemiological studies show a marked decline in infection among individuals under 40 years old. A significant reduction in vertical transmission and hepatocellular carcinoma incidence has also been documented in Spanish men aged 35–39 years. Although systematic vaccination has had a substantial impact on the HBV disease burden, challenges remain regarding surveillance in unvaccinated or vulnerable populations, especially in the context of migration movements.