Background:
Pertussis (whooping cough) is a highly contagious respiratory disease caused by Bordetella pertussis and remains a persistent public health challenge in Aotearoa New Zealand (Centers for Disease [1,2]. Epidemics occur every 3–5 years despite established vaccination programmes [3]. Infants and young children experience the greatest burden, with Māori populations facing disproportionately high hospitalisation rates [4]. At least 11 infant deaths have been recorded in the past two decades, and disruptions during the COVID-19 pandemic have widened existing immunisation gaps [5]. Currently, up to one-third of infants under six months are insufficiently immunised, increasing to one-half among Māori infants.

Methods:
This study will develop a mathematical transmission model of pertussis in Aotearoa New Zealand to better understand epidemic dynamics and population immunity. The model will incorporate age structure, vaccination status, waning immunity, and demographic differences, and will be parameterised using national administrative health data, including pertussis notifications, hospitalisations, immunisation records, and demographic information. The modelling framework will be used to examine how vaccination coverage, contact patterns, and underreporting influence epidemic timing and severity.

Results:
The model is expected to quantify transmission patterns across age groups and population subgroups, identify key drivers of recurrent epidemics, and estimate critical vaccination coverage thresholds required to reduce disease burden. It will also characterise inequities in risk, particularly among Māori infants and other vulnerable populations.

Conclusion:
This mathematical modelling framework will provide evidence to support more effective and equitable vaccination strategies and strengthen epidemic preparedness in Aotearoa New Zealand. The findings will inform public health policy aimed at reducing pertussis burden and addressing persistent health inequities.