Haemagglutination antibody titre levels which give certain protection against tetanus toxin.

The lowest haemagglutination titre which gives safe protection against tetanus toxin, in sera of vaccinated subjects of both sexes and of all age groups has been assessed, by comparative haemagglutination and neutralization tests. It was established that sera with 1/32 haemagglutination antibody titre have a toxin neutralizing capability of greater than or equal to 0.1 I.U./ml. Lower haemagglutination titers do not assure protective capacity against tetanus toxin.