Burnet Institute, Melbourne, Victoria, Australia. Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia. Australian Red Cross Lifeblood, Melbourne, Victoria, Australia. NSW Users and AIDS Association, Surry Hills, New South Wales, Australia. Kirby Institute, UNSW Sydney, Sydney, New South Wales, Australia. Haemophilia Foundation Australia, Malvern East, Victoria, Australia. Department of Gastroenterology, St Vincent's Hospital and the University of Melbourne, Melbourne, Victoria, Australia. National Drug and Alcohol Research Centre, University of New South Wales, Sydney, New South Wales, Australia. Department of Infectious Diseases, The Alfred Hospital, Melbourne, Victoria, Australia. Doherty Institute and School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia.