Citation

We validated a multiplex bead assay for diphtheria toxoid IgG antibodies against the Vero cell toxin neutralization test using 1300 specimens (correlation = 0.88). At the ≥0.01 IU/mL cutoff for minimal seroprotection, sensitivity was 95% and specificity was 83%. Agreement for three categories (<0.01, 0.01–<0.1, ≥0.1 IU/mL) was 81% (kappa = 0.71).