Yeast-derived hepatitis B vaccine in thalassaemic patients: a preliminary report.

Preliminary results of a trial involving a yeast-derived hepatitis B vaccine administered to 41 transfusion-dependent thalassaemic patients and 2 patients with spherocytosis are reported. Twenty-microgram doses of HBsAg were administered according to either a 0, 1, and 6 month or 0, 1, and 2 month schedule. Serum specimens collected prior to vaccination, one month after each vaccine dose, and again at 5 and 15 months, were tested for HBV markers and ALT. To date, seroconversion (anti-HBs titres greater than 10 IU/l) was observed in 15%, 67%, and 86% of patients one month following the three vaccine doses, respectively. Although the study is still in progress, a comparison of these results with those previously obtained using plasma-derived vaccine indicates that seroconversion to the recombinant yeast-derived vaccine is at least as high as that obtained by plasma-derived vaccines in patients affected by thalassaemia major.