PROJECT SUMMARY/ABSTRACT for Randomized COVID-19 Testing in Vulnerable Communities and Risk Tool Creation The broad objective of this project is first to perform community-engaged research using randomized COVID-19 tests among vulnerable populations in Milwaukee County, Wisconsin, and then to use innovative empirical methods to measure infection rates and progression risk, if infected, from symptomatic infection, to hospitalization, ICU admission, and death. This project is part of the NIH RADx-UP initiative to transform health through research and discovery in COVID testing among underserved populations. The 2-year project has three specific aims. Aim 1: Use randomized COVID antibody testing of more than 23,000 persons to measure the population proportion infected with COVID and how this proportion varies over time and with patient health and demographic characteristics. Twelve partner primary care health centers and 150 churches will support community engagement to achieve target enrollments for low-income, minority and elderly populations. These populations will be oversampled to obtain more precise estimates for these high-risk groups. Aim 2: Use extensive data linkages to health care data, virus testing data, and mortality records to estimate infection rates and progression risks as a multivariate function of patient and community characteristics. A web-based risk assessment tool in English and Spanish will be created to allow individuals, families, and health care professionals to assess individual progression risk and household transmission risk and to advise individuals on risk mitigation. This risk assessment tool will be informed by the Milwaukee data and will be of value nationwide. Aim 3: When COVID vaccines become available, the risk assessment tool will be used to inform the prioritization of vaccination of higher risk individuals. Established trusting relationships with primary care health centers and churches that serve vulnerable populations, social media outreach, community interest in COVID antibody test results, and easily accessed web-based consents, surveys, and risk assessment tools, as well as Community Advisory Board and focus groups input, will foster successful participation in this project. Random sampling methods will be used to estimate the population proportion infected as a function of demographic and health characteristics accounting for the potential for COVID virus testing, antibody testing, or both, to result in false negative test results. Population-representative estimates will be adjusted to account for oversampling of elderly, minority, and low-income populations, and for differences in response rates to the testing offers. To estimate progression risk, the tested population will be used to create a “synthetic” Milwaukee. This synthetic Milwaukee information will be combined with data on deceased patients and hospitalized patients to estimate progression risks. Core empirical methods innovations include: 1...