Is low immunisation coverage in inner urban areas of Australia due to low uptake or poor notification?

The Australian Childhood Immunisation Register (ACIR) consistently reveals pockets of lower immunisation coverage in inner urban areas. We investigated whether low uptake or poor notification of immunisation is the main reason for this difference.

We estimated under reporting by telephone surveying the parents of 640 children recorded as incompletely immunised on the ACIR at 12 months of age. Immunisation status was based on parental report of written records and/or date of receipt.

Of the 97 children living in inner urban areas (defined by postcode and population density), 55 (57%) were shown to be 'definitely immunised'. One hundred and thirty-four (53%) of the 253 children in other urban areas were shown to be 'definitely immunised'. Both these groups were significantly more likely to be 'definitely immunised' than the 104 (36%) of 290 children in areas outside capital cities (p < 0.0001).

Apparent lower immunisation uptake in inner urban areas of Australia may be attributable to reporting error.