We compared the long-term effectiveness of accelerated ( 0-1-2 months ) and standard ( 0-1-6 months ) hepatitis B vaccination schedules in preventing hepatitis B virus ( HBV ) infections and anti-hepatitis B ( anti-HBs ) antibody loss during 2-year follow-up in 707 drug users ( HIV and HBV negative at enrollment and completed 3 vaccine doses ) from February 2004 to October 2009 .