David is also Professor in Systems Immunology at Flinders University College of Medicine and Public Health, in Adelaide, South Australia. He leads an internationally regarded research program in systems immunology investigating how microbes (pathogenic and commensal) modulate the immune system in a range of contexts from infection to infant immunisation and cancer immunotherapy. He also has a strong interest in vaccine non-specific effects and trained immunity. Recent discoveries from his team include uncovering the role of the microbiota in vaccine responses, mammalian longevity  and cancer immunotherapies. His team were the first to show that, in mice, antibiotic exposure in early life leads to impaired responses to 5 different infant vaccines that are administered worldwide, leading to an Australian National Health and Medical Research Council (NHMRC) funded study in infants and significant funding from a major international vaccine company, in this area. David also leads a number of other clinical studies including the COVID-19 vaccine immune responses study; and the NHMRC-funded Antibiotics and Vaccine Immune Responses Study. David was also the PI in South Australia for the Gates Foundation-funded BRACE BCG vaccine randomised controlled trial. David has published 100+ peer-reviewed articles to date cited >10,000 times and in the last 10 years, was a Chief Investigator on projects worth >$30 million.