Compliance and immunogenicity of two hepatitis B vaccination schedules in sex workers in Belgium.

OBJECTIVES To compare the coverage for the third dose and the compliance to two hepatitis B vaccination schedules: 0,1,4 versus 0,1,6 months, in commercial sex workers (CSW) in Belgium; to compare the immunogenicity of the actually administered schedules. METHODS In seven health centres in Belgium, hepatitis B vaccination was offered free of charge to CSW. In a randomised, prospective study a commercialised hepatitis B vaccine (Engerix-B 20mcgr) was offered according to one of both schedules. After complete vaccination, bleeding was performed to assess immunogenicity. RESULTS Between June 2003 and September 2004, 615 non-immune CSW were enrolled, of whom 52% in the 0,1,4 month schedule (n=322). Coverage of the third dose was 57% overall, 59% (0,1,4) and 54% (0,1,6), respectively. Age, the health centre and drug use significantly influenced the compliance and the coverage of dose 3, whereas the planned vaccination did not. When comparing the immunogenicity results as a function of the actually administered vaccination schedule, immune responses did not significantly differ between CSW receiving the third dose 4-6 months and those receiving it at least 6 months after the first dose. In total, 19 persons (8%) were not protected after a full vaccination course (anti-HBs <10IU/L). Two health centres measured markedly lower anti-HBs levels. CONCLUSIONS In this highly mobile at-risk population, a 0,1,4 month schedule is more easy to offer and confers equal protection within a shorter period of time. We therefore propose this 0,1,4 month schedule to vaccinate CSW in the future.