A LONG-TERM FOLLOW-UP OF HEPATITIS-B VACCINATION IN PATIENTS WITH CONGENITAL CLOTTING DISORDERS

All patients with congenital clotting disorders attending our centre r outinely receive hepatitis B vaccination. We have assessed retrospecti vely the vaccine responses in 167 such individuals, with a follow-up p eriod of up to 7.5 years. The initial postvaccine anti-HBs response wa s lower in older patients (p=0.001), those infected with human immunod eficiency virus (HIV) (p = 0.05), and those who received intradermal r ather than subcutaneous administration of vaccine (p = 0.08). It was e stimated that the median time for anti-HBs levels to fall to 100 IU l( -1) was between 36 and 42 months, with a shorter period for older or H IV-infected patients. Although the persistence of protective antibody levels can be predicted to some extent from the absolute levels of ini tial postvaccine anti-HBs, the wide variation in antibody decline betw een individuals precludes recommendation of the timing of vaccine boos ter doses solely based on this value.