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Epidemiology of Tuberculosis and BCG Vaccine Uptake Among Pasifika in Aotearoa New Zealand

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Date

2025

Authors

Schutz, Rhonita

Supervisor

Charania, Nadia
Lolohea, Taniela
Paynter, Janine

Item type

Thesis

Degree name

Master of Public Health

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Publisher

Auckland University of Technology

Abstract

Tuberculosis (TB) has many known risk factors that contribute to its persistence worldwide, particularly in developing countries. Aotearoa New Zealand (NZ), as a high-income country, is fortunate to fall in the low-risk category. However, the incidence of TB is more common in particular ethnic groups such as Pasifika. The Pasifika population exhibit a unique set of vulnerabilities that increase their susceptibility to TB disease. Recent studies have reported a 13.1 per 100,000 notification rate for Pasifika in contrast to 0.5 per 100,000 among the European ethnic group in Aotearoa NZ. The Bacillus Calmette–Guérin (BCG) vaccine is the only licensed vaccine widely used to prevent TB. The World Health Organization (WHO) recommends BCG inclusion in neonatal vaccination schedules, depending on the TB epidemiology of the country. Many high incidence countries in the Pacific have been recommended to administer one dose to all neonates. However, countries with a low incidence of TB, such as Aotearoa NZ, can focus vaccination on high-risk groups only, through recommendation by healthcare workers to parents. Recommendation is based on specific eligibility criteria, meaning that all Pasifika children born in Aotearoa NZ are not necessarily entitled to BCG vaccination. Therefore, this study aims to identify strategies for improving TB prevention efforts by identifying the level of protection against TB for Pasifika. Given their higher TB burden and vulnerabilities, assessing the effectiveness of the BCG vaccination programme to capture at-risk populations is particularly important for these vulnerable ethnic groups. A Pasifika framework, Te Kora, was employed to guide a convergent parallel mixed methods design. To understand the epidemiology of TB and the BCG vaccine uptake among Pasifika in Aotearoa NZ, a quantitative observational study and a qualitative interpretive descriptive study were undertaken. TB and BCG data from 2006 to 2023 were descriptively analysed. Maroro (conversations) was used as the method to generate qualitative data to understand the perceptions of healthcare professionals on the BCG vaccination programme and TB prevention efforts. The qualitative data was then analysed with Conventional Content Analysis (CCA). The quantitative results showed that Pasifika and Asian populations in Aotearoa NZ had the highest TB incidence rates from 2006 to 2023, with average incidence rates of 11.4 per 100,000 (confidence interval (CI): 8.2 – 15.3) and 27.5 per 100,000 (CI: 23.5 – 32) respectively. Further analysis of the Pasifika population showed a higher percentage (average of 55%) of TB incidence among the less dominant Pasifika ethnicities such as Kiribati, Tokelau, Tuvalu and Niue. BCG vaccination rates were steadily high among the Asian population, with an average rate of 1000.7 per 100,000 (CI: 975.8 – 1026.2). BCG rates were also reasonably high among Pasifika, however, there was an observed rapid significant decrease to exceedingly low vaccination rates from 2011 to 2023. The average BCG vaccination rate for Pasifika was 519.4 (CI: 500.3 – 539.3) per 100,000, however, based on the significant decrease which reached vaccination rates as low as 26.6 per 100,000 (CI: 21.7 – 32.2), the Pasifika population were significantly under-vaccinated. Further analysis of the Pasifika vaccination rates indicated that Pasifika ethnicities were proportionately vaccinated relative to their population sizes except for the Cook Island Māori and Niuean ethnicities. This highlights the need for an increase in BCG vaccine uptake for the Pasifika population, especially among the less dominant Pasifika ethnicities, which have the highest proportion of TB notifications. Three main categories were constructed from the qualitative data that outlined barriers for the BCG vaccination programme and TB prevention efforts. These include systemic gaps in identifying at-risk groups, which identified knowledge gaps among healthcare workers and fragmented referral processes. The second category, perceptions of TB disease and BCG vaccine among migrants and Pasifika communities, identified stigma and migrants’ perception of TB risk. The third category is system-based factors that affect BCG uptake and TB reduction, such as the BCG policy and programme changes, the Pasifika umbrella, and effective communication. This study explored the effectiveness of current TB prevention efforts, particularly the BCG vaccination programme among at-risk populations in Aotearoa NZ with a focus on the Pasifika population. The findings highlighted specific barriers from the qualitative data that must be addressed in order to improve the current BCG vaccination programme. The study recommends system-level improvements to progress TB prevention among Pasifika, such as increasing training for healthcare workers to enhance risk assessment, uniform referral processes for all regions, disaggregated data, and health promotion strategies specifically to target TB stigma. The results of this work highlighted particular improvements that are needed to protect the Pasifika populations from TB.

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http://hdl.handle.net/10292/20187

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