The far-reaching impacts of the COVID-19 pandemic underscore the critical need for evidence-informed, transparent and inclusive decision-making. Policy-makers have grappled with complex choices amidst uncertainty. With the increasing threat of emerging pandemic-prone pathogens, new guidance released jointly by the World Health Organization (WHO), Organisation for Economic Co-operation and Development (OECD) and the World Bank elucidates the role of mathematical modelling – specifically integrated modelling – in addressing these challenges.