New methods to track progress toward elimination of sexually transmissible infections and blood-borne viruses in Australia

Abstract

The scale up of prevention, diagnostic and treatment initiatives across the world have led to substantial decreases in the burden of infectious diseases. The World Health Organization (WHO) sets elimination/eradication goals for infectious diseases that are suitable candidates for such initiatives. My thesis focused on measuring progress towards elimination of selected infectious diseases in Australia. Chapter 2 presents a systematic review of reports that described diseases targeted for elimination/eradication globally, the associated goals, terminology use, and validation processes. The review highlighted 26 infectious conditions that have been targeted for elimination/eradication and proposed a model to categorise different goals that will assist in establishing a more standardized approach to the development and communication of these initiatives. Chapters 3 and 4 focused on defining and tracking elimination of genital warts (GW) in Australia. Although Australia has observed substantial declines in GW due to implementation of the quadrivalent human papillomavirus (qHPV) vaccine in 2007 that protects against GW, there was no agreed upon elimination definition for GW. Chapter 3 reports a modified Delphi method to reach expert consensus on a GW elimination definition in the Australian context. Consensus was met that at ≥80% HPV vaccination coverage, GW will be eliminated as a public health problem by 2060, with a 95% reduction relative to 2006. Chapter 4 involved a cross-sectional analysis of routinely collected data from 34 sexual health clinics between 2004-2018 that focused on examining trends in GW diagnoses in locally- versus overseas-born patients (n=439,957), the first study to have examined this in Australia and internationally. The analysis showed reductions of 72%, 49% and 21% among Australian-, overseas-, and overseas-born patient from without qHPV/nonvalent (nHPV) vaccines, respectively. The reductions in Australian-born people reflects the efficacy of q/nHPV vaccines and the wide-spread vaccination coverage in Australia. However, population-wide elimination of GWs in Australia is dependent on other countries initiating or expanding their HPV vaccination programmes. Chapter 5 measured Australia’s progress towards the WHO goal of eliminating mother-to-child transmission (MTCT) of HIV, through a retrospective analysis of national surveillance data from 1988-2019 (n=887). The analysis showed an increase in the uptake of effective interventions to prevent MTCT. This led to a decline in the MTCT rate to zero, where women were diagnosed antenatally. However, when including women diagnosed postnatally, the MTCT rate was higher than the <2% elimination threshold set by the WHO. The analysis also indicated gaps in data for antenatal HIV screening and >40% of key demographic data were missing for mothers in recent years, suggesting a need for additional enhanced surveillance. My research has highlighted the importance of detailed assessments of progress towards elimination of infectious diseases. The findings will assist policy makers and health workers to identify gaps in the delivery of interventions and to enhance surveillance systems to capture necessary information to determine when Australia has met elimination goals for GW and MTCT-HIV.