 11 to 23 years after primary immunization, the study evaluates the long-term duration of the immunological memory of HBV vaccination in health care workers, HCWs, and students of health disciplines at Coreggi Teaching Hospital in Florence, Italy. The results show that an equal number of years has elapsed since vaccination, but administration during infancy induced lower long-term anti-HBS titers compared to those in case of vaccination performed during adolescence. A booster dose administered to subjects vaccinated in infancy is able to induce an amnestic immunological response in a higher percentage of vaccinated people. The total absence of acute hepatitis B among vaccinated subjects suggests that the long incubation period of the disease allows the activation of immunologic memory mechanisms, which is also true in case of low anti-HBS level. The study concludes that HCWs still represent a high-risk category and efforts should be increased to protect and vaccinate these subjects. This article was authored by Costanza Bini, Maddalena Grizzini, Martina Cellini, and others. We are article.tv, links in the description below.