Immunity and immunization of children against tetanus in sweden.

Tetanus antitoxin titres were determined in sera of 457 children, 6-, 10- and 16- year-old. Primary vaccination against tetanus had been given as 3 doses of DPT or DT vaccine at intervals of 4-6 weeks beginning in the 2nd or 3rd month of life. A booster dose is offered to schoolchildren at 8-10 years of age. As boosters, the children were given 0.1, 0.25 or 0.5 ml of diphtheria/tetanus toxoid (DT) containing 7.5 Lf/ml tetanus toxoid. The antitoxin titres against tetanus were much higher than those against diphtheria found in previous studies. Blood samples tested from 68 children, 5-year-old, who had been given basic immunization according to a spaced time schedule showed that 97% of the children had levels greater than 0.1 IU/ml. Prior to booster injection of the 6-year-old children, 1% lacked protective titre levels (greater than or equal to 0.01 IU/ml). 53% had antitoxin titre levels of greater than or equal to 0.01 - less than 0.1 IU/ml and 46% had levels of 0.1 IU/ml. The corresponding figures for the 10-year-old were 6, 65 and 29%, and for the 16-year-old 2, 7 and 91% respectively. After a booster injection high antitoxin levels were seen in all children. 95% had levels greater than 1 IU/ml irrespective of vaccine dose.