Financing Disease outbreaks are both lethal and costly. During 1997–2009, economic losses from six major outbreaks averaged $6.7 billion per year, and the cost of the 2014–2016 Ebola epidemic alone is estimated at $53 billion.3 Preparedness can prevent many outbreak-related costs, with estimated incremental worldwide expenditure of $4.5 billion per year needed to upgrade public health systems in low and middle-income countries, strengthen global institutions’ abilities to prevent and respond to emergencies, and invest in research and development of new vaccines, diagnostics and countermeasures for epidemic and pandemic-prone diseases.4 Unfortunately, preparedness, although more effective and less costly than response,5 rarely ranks high on political agendas. Competing priorities for finite national budgets, along with the invisible outcome of successful preparedness, have resulted in little funding, despite an estimated 25%–88% annual return on investment.6 Vulnerable lower income countries have bigger gaps and greater need for external financing. Of the 24 least-prepared countries,2 20 (83%) are sufficiently low income to be eligible for International Development Association (IDA18) from the World Bank.7 In these countries, there are limited resources and competing demands, with the result that public health is often a low priority.8 The World Bank has recently dedicated additional support for health security in these settings through specific IDA projects such as the Regional Disease Surveillance Systems Enhancement project.8 Regional development banks can develop similar credit or grant programmes to build public health capacity in countries and protect regions from the economic shocks of large-scale outbreaks, as the Asian Development Bank has done.9