HBV seroprevalence after 25 years of universal mass vaccination and management of non-responders to the anti-Hepatitis B vaccine: an Italian study among medical students

According to international guidelines, healthcare workers and medical students immunized against HBV are periodically tested for anti-HBs IgG. Subjects who show an anti-HBs titer <10 mUI/ml must receive additional vaccine doses to induce a measurable antibody response. This study aimed to evaluate the long-time immunogenicity of anti-hepatitis B vaccination in a sample of medical students and residents of the University of Bari who attended the Hygiene Department for biological risk assessment (April 2014 - June 2017). The strategy for the management of non-responder subjects was evaluated. 3,676 students and residents were invited for testing according to a standardized protocol. Anti-HBs IgG was tested for in 3,140 (85.4%) subjects: 1,174/3,140 (37.7%) subjects were negative. 14.6% (128/808) of subjects who received the vaccine during their 12th year of life and 45.8% (1,056/2,305) ofsubjects immunized during the first year of life (p<0.0001) were negative. 1,005/1,174 (85.6%) seronegative subjects received a booster dose and 903/1,005 (89.9%) were tested for anti-HBs one month after the booster dose: 82/903 (9.1%) subjects were still negative. Of these, 56/82 (68.3%) received two additional doses of vaccine and 52/56 (92.9%) were tested one month after the third dose: 50/52 subjects (96.2%) developed a positive titer. In conclusion, several medical students, immunized at birth or at young age against HBV, did not develop protective titers against the virus. Our management strategy (booster- re-test; for negative subjects, two doses and re-test) seems consistent with the purpose of evidencing immunological memory. This article is protected by copyright. All rights reserved.