Vaccine preventable diseases
Creators: name: Chiew, May
Publisher: name: The Australian National University
Year: 2014

description: Vaccination is one of the most significant public health interventions in history. In this thesis, I present work conducted as an Master of Applied Epidemiology (MAE) Scholar whilst placed at the National Centre for Immunisation Research and Surveillance (NCIRS) in 2012-2013. During my placement, I was involved in examining the epidemiology of a number of vaccine preventable diseases and also adverse events following immunisation (AEFI). A key requirement of the MAE is the analysis of a public health dataset; of which I present two analyses. Firstly, the impact of the human papillomavirus vaccine on high grade cervical abnormalities (HGAs) in Australia using screening data; the analysis found a significant reduction in HGAs in females under 20 years post-vaccine compared to the pre-vaccine era, suggesting that the vaccine may have contributed to the decline in HGAs.Secondly, the epi-review on passive AEFI surveillance in children less than 18 years of age in 2000-2011 highlighted major events that occurred during this period. I also present two projects conducted as part of the measles outbreak in New South Wales (NSW) during 2012. The first was using a non-validated algorithm to identify an index case following four measles notifications that were linked by time and place to a paediatric hospital. The algorithm was unsuccessful in identifying an index case, however, may serve as a model that can be adapted and possibly validated for use in similar investigations in the future. The second was examining the epidemiology of healthcare transmissions during the outbreak. This study identified the importance of raising awareness of measles among clinicians during outbreaks and that measles control strategies may need a more targeted approach, particularly with limited resources. As part of my epidemiological study, I conducted an epi-review of measles in Australia. Since 1993, there was a considerable decline in measles notifications and hospitalisations; however; between 2000 and 2011, notifications have fluctuated with a notable increase in 2011. National notification data (2009-2011) were also used to estimate the reproduction number (R) for measles. The three methods to estimate R were below one for all years suggesting that measles elimination had been sustained in Australia. I also calculated a measles discard rate in NSW; an indicator of high quality surveillance. This study further supported sustained measles elimination achieving the minimum standard of more than 2 non-measles cases per 100,000 population suggesting that in NSW, endemic measles would be detected if wild virus was re-established. I also present another MAE requirement, evaluating the passive surveillance system for varicella-zoster virus nationally, as part of the National Notifiable Disease Surveillance System. I found that the sensitivity of the system in detecting the incidence of disease was poor; however, it was sensitive in detecting disease trends when compared to other data sources. Additionally, more consistency in reporting by jurisdictions is necessary to improve the validity of the data. This thesis provides documentation of my MAE activities at NCIRS and includes how these activities have contributed to public health in Australia.