Evaluation of Indigenous status completeness in vaccine preventable disease notification data in the NNDSS

High quality Indigenous status data for vaccine preventable diseases (VPDs) in the National Notifiable Diseases Surveillance System (NNDSS) is important for evaluation of immunisation programs and ultimately for improving health outcomes for Aboriginal and Torres Strait Islander peoples. We evaluated Indigenous status completeness, and factors influencing it, for VPDs in the NNDSS.

Literature review (published and grey); descriptive analysis of NNDSS data for selected VPDs over the 2010-2019 period; standardised online survey (containing closed- and open-ended questions) of key informants; semi-structured follow-up interviews.

National level Indigenous status completeness for those VPDs with a Communicable Diseases Network Australia (CDNA) target of 95% was above that target for Haemophilus influenzae type b, measles, invasive meningococcal disease and invasive pneumococcal disease (IPD: < 5 and ≥ 50 years); and was within four percentage points for hepatitis A, newly acquired hepatitis B and pertussis (< 5 years). For VPDs with an 80% target, completeness was ≥ 90% for diphtheria, mumps, rubella and tetanus; ≥ 80% for IPD (≥ 5 to < 50 years); and below target for unspecified hepatitis B (54%), laboratory confirmed influenza (47%), pertussis (≥ 5 years; 60%) and rotavirus (71%). However, completeness was above 90% for all VPDs in the Northern Territory, and all except laboratory confirmed influenza (89%) in Western Australia. Key barriers to Indigenous status completeness include the absence of an Indigenous status field on most pathology request forms and limited public health authority resource capacity to follow up missing data, particularly for high incidence diseases.

National level Indigenous status completeness is high for most VPDs but low for others, particularly for high incidence diseases predominantly notified by laboratories. Completeness is uniformly high for all VPDs in the Northern Territory and Western Australia; however, this is due to the resource-intensive public health follow-up of all notifications and manual cross-checking of other databases when Indigenous status is missing. To more efficiently optimise Indigenous status completeness in the NNDSS across all jurisdictions, a mix of additional strategies is needed to ensure accurate identification and recording in primary care, hospital, laboratory and public health settings, and effective transfer between them.