The effectiveness of a formalised opportunistic immunisation system in a hospital setting was evaluated using data from a cohort of 5583 children in the National Immunisation Register cohort seen in a hospital setting, 1641 (29.4%) of whom were under-immunised, compared with the concurrent regional cohort of 15%. Māori children were less likely to be age-appropriately immunised (36.9% under-immunised; p<0.0005). Of the 1641 under-immunised children, 337 (20.5%) were deemed to have current medical reasons not to be immunised acutely, and of the remaining 1304, 244 (18.7%) declined immunisations. Immunisation was therefore possible for 1060 children; 880 (83.0%) of them were immunised. All children were re-engaged with primary care services.
