Tetanus antibodies as a marker of potential efficacy of killed polio immunization.

The use of antibodies to tetanus toxin as a marker of efficacy of parenteral immunization was examined in a randomized sample of 1212 sera representative of the total black infant population of the RSA between 24 and 35 months. All but one of these sera had protective levels of antibodies measured by enzyme-linked immunosorbent assay. In contrast, in a previous study only 59-80% had tritypic immunity to polio and 70-84% mono- or bitypic immunity. Thus, this serological marker was found to be unreliable and some possibilities for this remarkably high level of antitetanus antibodies are considered.