Gerard is an epidemiologist and international disaster health specialist. He spent his early career in government statutory roles in infectious disease management working in regional health and Aboriginal medical services in New South Wales and Victoria. From 2002 his focus shifted toward health and humanitarian aid and since then he has worked for international non-government organisations, foundations and united nation programmes providing expert technical advice on health projects and disaster health responses in over 30 countries across Africa and Asia. This involved the design and implementation of sustainable health programming and emergency health and medical responses to disasters, such as floods, cyclones, earthquake, drought, disease outbreaks and smoke haze crises. Gerard has led large teams of international subject matter experts in economics, agriculture, health, and human rights to respond to contemporary global humanitarian policy debates about maternal mortality, climate change and global child health. He is the principal author on official policy submissions on the Sustainable Development Goals, climate change threats to health and the global health initiative. His work is recognised as part of the UN flagship report on global disaster threats (GAR2019) and he served as the expert peer reviewer of the disaster epidemiology chapter of the WHO textbook on health emergency research and disaster risk management. The COVID-19 pandemic necessitated his return to directly supporting emergency health and medical responses including as the senior epidemiologist for vaccine safety in Victoria and as the WHO senior epidemiologist and pillar lead for 21 Pacific Island countries and areas in the WHO DPS region.