[Function of tetanus immunoglobulin in case of injury: administration often unnecessary]

To calculate the number of tetanus immunoglobulin (TIG) injections given in order to prevent one patient developing tetanus (number needed to treat (NNT)) and the accompanying costs.

Functional study.

The risk of developing tetanus was calculated from the results of a national study on tetanus immunity in the general population of the Netherlands (1995-1996; n = 7715) and from official notifications of tetanus in the period 1984-1996 (n = 30 persons born before 1945). According to current vaccination policy TIG is advised for unvaccinated persons and those with an unclear vaccination status as well as those vaccinated more than 15 years ago.

The tetanus risk after injury was estimated at 0.5-2 per million for unvaccinated individuals. Immunity was lowest (< 50%) in men born before 1936 and women born before 1950. The NNT for these groups was a minimum of 530.000. With a mortality of 10% and costs of 20 Euro per TIG injection, the cost of each life saved was found to be a minimum of 105 million Euro. The NNT and cost per life saved were astronomical for those persons born after 1955.

The current TIG policy is inefficient. Thanks to the success of the National Immunisation Programme it is now justified to limit the administration of TIG to those who are at the highest risk i.e. those who are known to be unvaccinated, women born before 1950 and men born before 1936.