Reporting of pregnancy vaccinations across two data sources, New South Wales, Australia, 2017-2022.

Objectives Timely, accurate reporting of pregnancy vaccination coverage is key to evaluating pregnancy immunisation programs. We compared influenza and pertussis vaccination reporting on the New South Wales (NSW) Perinatal Data Collection (PDC) and the Australian Immunisation Register (AIR), to understand coverage, reporting, timing of vaccination and provider type. Methods This retrospective population-based cohort study in New South Wales, Australia, included people giving birth at ≥20-weeks' gestation (2017-2022) in the NSW PDC (total number of pregnancies 555,553), linked to AIR-reported influenza and pertussis vaccinations. Main outcomes of interest were influenza and pertussis coverage according to 1) the PDC and 2) linked AIR records. We assessed agreement between data sources (i.e. whether an AIR record during the pregnancy existed if vaccine receipt was reported on the PDC, and vice versa) by year (influenza: 2021-2022, pertussis: 2017-2022) and selected characteristics (2022). Provider type and timing for vaccinations reported to the AIR are described (2022). Results PDC-reported influenza and pertussis coverage peaked in 2020 (influenza: 58.8%, pertussis: 79.0%), decreasing thereafter (influenza: 49.1%, pertussis: 77.6% in 2022). AIR-reported influenza and pertussis vaccination coverage increased (influenza: 34.7% in 2021 to 44.8% in 2022; pertussis: 24.4% in 2017 to 51.6% in 2022). Agreement between AIR and PDC improved over time, but remained suboptimal (influenza: 75.5%, pertussis: 56.6% in 2022). AIR and PDC agreement differed most by antenatal care model, particularly for pertussis vaccinations. In 2022, of pregnancy vaccinations reported to the AIR, >75% were provided in general practices. Co-administration occurred infrequently (8.8%). Conclusions Despite mandated reporting to the AIR, there was significant underreporting of pregnancy vaccinations to the AIR as compared with the NSW PDC. National collection of accurate and timely data on pregnancy vaccination coverage is needed to monitor vaccine uptake, and identify and monitor strategies to improve uptake, particularly with the new pregnancy respiratory syncytial virus vaccine program in 2025. We identified co-administration as a potential strategy to improve influenza vaccination coverage during pregnancy.