A new national health system: the opportunity to address data quality issues in maternal immunisation coverage.

AIM: Maternal immunisation coverage is suboptimal in Aotearoa New Zealand. Our objective was to highlight discrepancies resulting from how maternal immunisation coverage for pertussis and influenza is measured in Aotearoa New Zealand. METHOD: A retrospective cohort study of pregnant people was undertaken using administrative datasets. Maternity and immunisation data from three sources (National Immunisation Register [NIR], general practice [GP], and pharmaceutical claims) were linked to determine the proportion of immunisation records not recorded in the NIR but captured in claims data, and to compare this with coverage data available from Te Whatu Ora - Health New Zealand. RESULTS: We found that while increasing numbers of maternal immunisations are being captured in the NIR, around 10% remain unrecorded on the NIR, but within claims datasets. CONCLUSION: Accurate maternal immunisation coverage data is important for public health action. Implementation of the whole-of-life Aotearoa Immunisation Register (AIR) is an important opportunity to improve completeness and consistency of maternal immunisation coverage reporting.