Immunization status and demographic characteristics of New Zealand infants in the first 6 months of life.

In the Royal New Zealand Plunket Society's 1990-91 cohort study, of 3902 children, 985 (25.2%) had fallen behind the immunization schedule by 6 months of age. These children were more likely to be from lower socio-economic groups or to have mothers who were older, with high or low education, or of higher parity. The infants were also more likely to be from non-European families, or to have unemployed fathers. Eight hundred and ten (82.2%) of the incompletely immunized children at that age could be brought up-to-date with their immunizations by a single visit to the doctor. The most common reason for delaying immunization was that the baby was sick. This was a false contraindication in 69.2, 79.0 and 78.4% of these children at the 6 week, 3 month and 5 month immunization, respectively.