Hepatitis B Seroprevalence in the Pediatric and Adolescent Population of Florence (Italy): An Update 27 Years after the Implementation of Universal Vaccination.

Background: Hepatitis B still represents a health concern, although safe and effectivevaccines have been available since 1982. Italy introduced a program of universal vaccination againsthepatitis B in 1991. The aim of this study was to assess the immunity levels towards hepatitis B in asample of sera from the pediatric and adolescent population in the province of Florence, CentralItaly, twenty-seven years after the implementation of universal vaccination. Methods: A total of 165sera samples were collected from the resident population of Florence aged 1–18 years. The anti-HBsand anti-HBc enzyme-linked immunosorbent Assay (ELISA) tests were performed on all samples.The anamnestic and vaccination status data were also collected. Results: Seroprevalence of anti-HBswas approximately 60%, with children aged 1–5 years having the highest positivity rate (81.6%),and decreasing trends in the older age groups. The zero prevalence of anti-HBc shows that thedetected protective immunity is mainly due to vaccination, and natural infection was not reportedin the studied population. Conclusions: The seroprevalence of anti-HBs and the lack of anti-HBc inthis study highlights that immunity levels have been derived mainly from immunization. Thisconfirms how vaccination dramatically reduced circulation of the hepatitis B virus in Italy in thepediatric and adolescent population twenty-seven years after implementation of the mandatoryuniversal program.