The relative immunizing efficiency of tetanus toxoid preparations.

The results of comparative assays have revealed considerable variation in the potencies of tetanus toxoids produced in different laboratories. Some manufacturers are able consistently to produce toxoids high in potency; others are not able to do so. While further work is required in order to correlate the animal assay with results in man, these results once more stress the inadequacies of minimum requirement tests used in most countries for controlling products of this type and the need for more precise methods of control.