PROJECT SUMMARY: The novel Severe Acute Respiratory Syndrome (SARS) Coronavirus 2 (SARS-CoV-2 or COVID-19) pandemic has exacted a grievous toll on human existence exacerbating underlying disparities and disproportionately impacting minority, impoverished and elderly populations. Moreover, testing and contact tracing have been identified as critical for reducing community transmission, yet uneven access by race/ethnicity, income and geography limit effectiveness. Proposed is a cluster-randomized trial of testing modalities with longitudinal follow-up in an urban city with COVID-19 disparities illustrative of national trends. We propose the following Specific Aims: 1) To determine multilevel (socioeconomic, behavioral) barriers and facilitators to SARS-CoV-2 testing using a population representative sample of households in Baltimore, MD; 2) To define the optimal SARS-CoV-2 testing modality for maximizing testing acceptance, uptake and timeliness of providing results through a cluster-randomized comparative effectiveness trial; 3) To evaluate the impact of testing modality and receipt of positive results on subsequent testing behavior and other behavioral, economic and clinical outcomes; and 4) To serve as a platform for future investigations related to SARS-CoV-2 transmission and COVID-19-associated morbidity and mortality. We will recruit a population representative sample of ~1,300 households in Baltimore City. Two-stage sampling will select census block groups (CBGs) and households within CBGs with oversampling to ensure representation of vulnerable groups. Of 105 selected CBGs, 36 clusters will be allocated in a stratified randomization approach to one of three testing modalities including: 1) self-administered home collection (swab/saliva/blood) kit sent to home with return packaging; 2) referral to a community-based mobile testing van; or 3) referral to the nearest fixed testing site (as optimized standard of care). All household members will be randomized to the same modality. The primary outcome will be timely completion of testing and receipt of results; secondary outcomes will include the proportion undergoing testing, and time from testing to receipt of results. During six months of follow-up, we will monitor households for new onset COVID-19 symptoms and exposures and if evident, offer re-testing by previously assigned modality. In addition to testing outcomes described in Aim 2, we will examine individual and household-level behavioral (e.g., adherence to self-isolation, social distancing, mask wearing), economic (e.g., unemployment, time to return to work, housing instability), and clinical outcomes (e.g., severity of infection, hospitalization, mortality – endpoints which can uniquely be captured systematically through linkage with a Maryland State health information exchange linkage. High-quality evidence from this comprehensive effort will identify multifactorial drivers of testing disparities, provide rigorous data for the most ef...