“…Several studies [106,113,114,123,132,151] evaluated the long-term efficacy of the vaccine in HD patients and reported a decline of anti-HBs titers within 6 months to 4 years after vaccination. In a recent series [152], 36% (21/ 58) of HD patients showed loss of detectable anti-HBs titers over a 34-month follow-up; older age and longer duration of HD treatment were correlated with the decline of anti-HBs titers over time.…”