Diphtheria immunity in New Zealand children.

A Schick survey of 689 children was carried out in the Wellington health district during winter 1981. Only 25 (3.6 percent) were found to be non-immune. Although this appears to indicate a high level of herd immunity in school children, the results must be interpreted with caution. Because cases of diphtheria are still occurring in New Zealand, it is argued that unless efforts are made to raise the level of infant immunisation, this country cannot be considered free from the threat of an increase in clinical diphtheria, particularly among non-Europeans.