RANDOMIZED, COMPARATIVE TRIAL OF 20 MU-G VS 40 MU-G ENGERIX-B VACCINEIN HEPATITIS-B VACCINE NONRESPONDERS

Fifty-two adults who had previously received 4 x 20 mu g doses of hepa titis B [Engerix-B] vaccine (appropriately administered into the delto id muscle) and who had failed to develop detectable anti-HBs were rand omized to receive a fifth dose of Engerix-B (either 20 lug or 40 mu g) intramuscularly (deltoid). The participants were blinded as to the co ntents of the syringe. Anti-HBs was tested (by EIA) 3 months after the injection. Anti-HBs results from 45 non-responders were evaluable. Se ven vaccinees were excluded; four of these on the basis of failure to have follow-up blood collected and three who were found to be anti-HBc positive (one HBsAg positive). Twelve of 22 (54.5%) of those receivin g 20 mu g of HB vaccine developed anti-HBs, whereas 10 of 23 (43.5%) w ho received 40 mu g developed anti-HBs, showing no significant differe nce between the regimens. The mean geometric titres were 93 +/- 50 and 86 +/- 51 IU l(-1), respectively. Vaccinee groups were well matched f or age, sex and body mass index and the interval between injection and bleeding. Side-effects in those receiving the double (40 mu g) dose w ere no different from those receiving the normal (20 mu g) adult dose. On the basis of this study, a fifth dose of vaccine in non-responsive vaccinees is recommended. No significant advantage of 40 mu g over 20 mu g of vaccine was observed. Whilst smoking and obesity were common in this cohort of non-responders and probably contributed to the indiv iduals primary non-responsive state, these factors had no unfavourable effect on response to a fifth dose of vaccine. (C) 1997 Elsevier Scie nce Ltd.