High chance to overcome the non-responder status to hepatitis B vaccine after a further full vaccination course: results from the extended study on healthcare students and workers in Florence, Italy.

Healthcare workers (HCWs) are considered high-risk subjects for Hepatitis B Virus (HBV) infection due to occupational exposure to blood and body fluids. Vaccination represents the core strategy for HBV infection prevention. Following our previous publication on this topic, we aimed to assess the effectiveness of booster vaccine doses in eliciting the immunological response in seronegative (<10 mIU/mL) HCWs and students of Careggi Teaching Hospital, Florence (Italy). All subjects received primary vaccination course, and they were tested for serum anti-HBs antibodies. In seronegative subjects, a challenge dose of vaccine was administered and the test was repeated 1 month later. Six hundred and ninety-eight (87.8%) of 795 HCWs and students tested responded to the challenge dose. After this challenge dose, males more often had negative anti-HBs titer compared with females (15.9% vs 10.2%; p < .05). The completion of the second vaccination course was offered to subjects with persistently negative anti-HBs titer. 76.2% (32) of those who accepted the fifth dose, and 3 of the 5 who accepted the sixth dose seroconverted. This report shows the importance to convey a strong message to negative subjects at the initial anti-HBs dosage: accepting all the three additional vaccine doses allows the vast majority of them to obtain protection.