1. Hunter New England Population Health, Hunter New England Local Health District , Newcastle, NSW 2305, Australia
2. University of Newcastle School of Medicine and Public Health, , Newcastle, NSW 2308, Australia
3. Public Health Response Branch, New South Wales Ministry of Health , Sydney, NSW 2060, Australia
4. University of Western Sydney School of Medicine, , NSW 2052, Australia
5. Australian National University National Centre for Epidemiology and Population Health, , Canberra, ACT 2601, Australia