Abstract
Group A Streptococcus (Strep A) leads to 600,000 deaths and 600 million cases of pharyngitis annually. Although long a promising target for vaccine development, how much funding should be allocated to develop a Strep A vaccine is unclear. We aim to calculate the optimal amount of global spending for Strep A vaccine development, the resulting benefits, and the social rate of return on this spending. We develop a model of optimal spending, from a global societal perspective, on research and development (R&D) for vaccines and treatments. The model takes as inputs total harm from the disease, the probability an R&D project succeeds, the cost of a project, and the fraction of total harm a success alleviates. Based on these inputs the model outputs an optimal amount of spending and a rate of return. We calibrate the model for Strep A. Optimal spending is estimated to be 2020 USD33 billion. This spending leads to 2020 USD1.63 trillion in benefits and a real return of 22.3% per year for thirty years. Sensitivity shows an optimal spending range of 15.9 billion to 58.5 billion, a benefits range of 1.6 trillion to 37.9 trillion, and a return range of 18.0-48.2%. Investment in a Strep A vaccine could create enormous benefits for comparatively little cost. It represents one of the highest return uses of public spending. Policy can promote Strep A vaccine development through direct funding of projects and by promoting financial mechanisms that allow the private sector to diversify its R&D investment.