Immunisation, Infectious Diseases, and Environmental Health: Applied Epidemiology in Tasmania and the Latrobe Valley, Victoria

Abstract

This thesis presents work completed for the Master of Philosophy in Applied Epidemiology (MAE). My first placement was at the Communicable Disease Prevention Unit at the Tasmanian Department of Health, where I completed my first three projects. My second placement was at the Environmental Health Group, Menzies Institute for Medical Research, University of Tasmania, where I completed my final project. I evaluated the Tasmanian adverse events following immunisation (AEFI) surveillance system, using the framework described in the Center for Disease Control's Updated Guidelines for Evaluating Public Health Surveillance Systems. This project comprised both qualitative elements, namely interviewing of identified stakeholders, and also quantitative data analysis of the surveillance system dataset. I demonstrated that the Tasmanian AEFI surveillance system requires low resources, is stable, simple, fairly flexible, and with evidence of geographically and demographically representative data. However, several limitations were identified, including poor data quality, low awareness of the system in AEFI reporters, evidence of underreporting and low sensitivity, poor timeliness, limited usefulness, and some missed opportunities to engage in dialogue with consumers and vaccine providers about vaccine safety. I made several recommendations for improvements to the system. For my major epidemiological study, I evaluated the first five months of the Tasmanian Meningococcal W Vaccination Program in schools. This program was rapidly rolled out in July 2018 in response to the emergence of meningococcal serogroup W disease in Tasmania, targeting all Tasmanians aged 15-19 years and primarily using school-based delivery. A major component of the evaluation was a process evaluation assessing council and school perspectives of the program, using focus groups and an online survey respectively. The evaluation identified several strengths and challenges, informing some modifications to the program. Additionally, it gave valuable insight into barriers to immunisation in the school setting in Tasmania, which has wider relevance to ongoing meningococcal and other routine school-based immunisation programs. For my acute public health problem investigation, I led a case-case study to investigate a cluster of Salmonella Typhimurium cases in Tasmania, using notified Salmonella Mississippi cases as the comparison group. This study unfortunately was limited by fluctuating case numbers and did not include a large enough sample to identify the source of the cluster, and importantly was unable to support or refute the hypothesis that fresh chicken was the source. Nevertheless, lessons learned from this project, including on case-case methodology and appropriate selection of cases, were useful both to myself and the Communicable Disease Prevention Unit. My fourth project was the analysis of a dataset collected as part of the Hazelwood Health Study Latrobe Early Life Follow-up Cohort Study. This study aims to understand the impact of the February 2014 Hazelwood coal mine fire in the Latrobe valley, Victoria, on the health of children exposed to coal mine fire smoke in utero or in early childhood. I analysed baseline survey data and monthly health diaries collected between June 2016 and October 2018 for a subset of children enrolled in the cohort study, to evaluate the association of coal mine fire smoke exposure (both in utero and in early childhood) on parent-reported respiratory and atopic health outcomes. This analysis forms part of a new body of evidence describing the health impact of the coal mine fire and has important implications for both the Latrobe valley community, and for the future public health management of similar severe smoke events. Show more