A randomized comparison between early and late vaccination with tetanus toxoid vaccine after allogeneic BMT

Forty-five adult HLA-matched sibling BMT recipients were randomized to receive tetanus toroid (TT) vaccine at 6, 8 and 14 months (early group, n = 23) or at 18, 20 and 26 months after BMT (late group, n = 22). At 6 months after BMT, prior to the first vaccination, 90% of the early group patients had a protective tetanus antibody concentration of greater than or equal to 0.1 HU/ml (passive haemagglutination test) but only 70% of the late group patients did so at 18 months after BMT. The antibody responses 1 month after each of the three TT vaccine doses were similar in the two vaccination groups, except that after the first dose, four-fold responses occurred more frequently in the late group. All vaccinated patients achieved the protective antibody concentration of greater than or equal to 0.1 HU/ml. In the late group the recipient antibody responses after the first and second vaccine doses correlated with the donor anti-TT level. A tetanus vaccination schedule consisting of three vaccine doses is equally immunogenic when started at 6 or 18 months after BMT. Donor immunity against tetanus may influence recipient responses to TT vaccination.