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 effective vaccines have been available since 1982. Italy introduced a program of universal vaccination against hepatitis B in 1991. The aim of this study was to assess the immunity levels towards hepatitis B in a sample of sera from the pediatric and adolescent population in the province of Florence, Central Italy, twenty-seven years after the implementation of universal vaccination. Methods: A total of 165 sera samples were collected from the resident population of Florence aged 1-18 years. The anti-HBs and 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-HBs was 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 the detected protective immunity is mainly due to vaccination, and natural infection was not reported in the studied population. Conclusions: The seroprevalence of anti-HBs and the lack of anti-HBc in this study highlights that immunity levels have been derived mainly from immunization. This confirms how vaccination dramatically reduced circulation of the hepatitis B virus in Italy in the pediatric and adolescent population twenty-seven years after implementation of the mandatory universal program.