Tradeoffs Between the Equal and Equitable Distribution of a Scarce Health Resource: Evidence from a Large Randomized Natural Experiment with Targeting by Health, Social Vulnerability, and Race The recent pandemic and supply chain disruptions have created scarcities in life-saving health resources from ventilators to vaccines, highlighting the need for evidence-based guidance on how to navigate tradeoffs in distributing them. Policy responses to scarcity have important implications for large and widening disparities by health, social vulnerability, and race. Our long-term goal is to inform evidence-based policies to address inequities and improve public health when resources are scarce. Our objective is to use economics to analyze a tradeoff between two key goals. One is equality: the same chance at early access for all subgroups of a population. Another is equity: the same average outcomes for all subgroups of a population. We are uniquely positioned to overcome a major barrier to understanding tradeoffs between the equal and equitable distribution of vaccines and other scarce health resources by applying rigorous methods from economics to a credible research design based on a large randomized natural experiment that randomized early access to vaccines to a large population of patients age ≥65 when doses were extremely scarce. We have three specific aims. Aim 1: Estimate inequities in vaccine takeup along many detailed dimensions of health, social vulnerability, and race using equality in early access via random assignment and rich data that we construct and disseminate. This aim will analyze inequities in a large novel dataset constructed by linking randomized invitations to electronic health records, survey data, and population-level data from vaccination, death, salary, and voter registries, which we will share. This aim will also contextualize inequities from our randomized setting using national population-level vaccination, health, and voter data to inform the impact of further policies that target by geographic vs. individual characteristics. Aim 2: Quantify how much of the inequities by health, social vulnerability, and race that persist given equality in early access via random assignment can be explained by various mechanisms that operate through health behaviors, health conditions, and social and environmental factors available in our electronic health records and survey data. This aim will quantify the potential equity impacts of policies that address various mechanisms such as distance to vaccination sites using approaches that go beyond targeting greater numbers of invitations. Aim 3: Characterize how the composition of the vaccinated population changes by health, social vulnerability, and race as the share vaccinated expands with randomization, and relate those changes to inequities in downstream impacts of vaccination on health and economic wellbeing. This aim will inform the potential for vaccine distribution policies to affect c...