Patterns of reporting of influenza and pertussis vaccination during pregnancy to the Australian Immunisation Register, 2022

ObjectivesTimely, 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. DesignRetrospective population-based cohort study. SettingPeople giving birth at [≥]20-weeks gestation (2017-2022) in the NSW PDC, linked to AIR-reported influenza and pertussis vaccinations. Main outcome measuresInfluenza and pertussis coverage according to 1) the PDC and 2) linked AIR records, and agreement between data sources by year (influenza: 2021-2022, pertussis: 2017-2022) and selected characteristics (2022). Description of provider type and timing for vaccinations reported to the AIR (2022). ResultsPDC-reported influenza and pertussis coverage peaked in 2020 (influenza: 58.8% (52,940/90,091), pertussis: 79.0% (71,169/90,091)), decreasing thereafter (influenza: 49.1% (43,744/89,112), pertussis: 77.6% (69,129/89,112) in 2022). Influenza and pertussis vaccination coverage as reported to the AIR increased from 34.7% (33,611/96,789) in 2021 to 44.8% (39,935/89,112) in 2022 and 24.4% (22,857/93,582) in 2017 to 51.6% (46,009/89,112) in 2022, respectively. 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%). ConclusionsDespite 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 RSV vaccine program in 2025. We identified co-administration as a potential strategy to improve influenza vaccination coverage during pregnancy.