Immunoglobulin E responses to diphtheria and tetanus toxoids after booster with aluminium-adsorbed and fluid DT-vaccines

Immunoglobulin E responses to diphtheria and tetanus toxoids were investigated in pre- and postbooster samples of 104 children given, at 10 years of age, a DT booster with either an adsorbed (n = 51) or a non-adsorbed, fluid vaccine (n = 53). Vaccination with adsorbed DT is part of a national immunisation programme and represents the first regular booster given to these children, primarily immunised with three doses of adsorbed DT at age 3–6 months. The vaccines, with a content of 30 Lf of diphtheria toxoid and 7.5 Lf of tetanus toxoid per millilitre, were given for booster in a dose of 0.25 ml as a deep subcutaneous injection. In the prebooster samples, 3 and 14% had measurable IgE to diphtheria and tetanus, respectively. These rates rose to 94 and 92% in the postbooster samples, respectively. The median (range) of IgE to tetanus among recipients of the adsorbed vaccine was 0.59 PRU ml−1 ( 0.5) but the two IgE responses as well as the ratios of IgGIgE showed strong correlations (r > 0.7, p < 0.001). The study thus revealed unexpectedly high rates of IgE responses to diphtheria and tetanus toxoids in a regular DT booster vaccination programme, which were associated to high rates of local side effects. The clinical significance of the findings remains to be elucidated but aluminium as adjuvant may need re-evaluation.