This chapter covers the development of diagnostic tests that detect and often amplify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acids (molecular tests) or directly detect protein antigens (antigen tests). In the Rapid Acceleration of Diagnostics (RADx®) Tech program, tests that could be performed by following the instructions for use (Clinical Laboratory Improvement Amendments-waived point-of-care tests) or at home (over the counter) became more ubiquitous and represented a paradigm shift in infectious disease diagnostics away from reference laboratory testing by trained laboratorians. Understanding the clinical use case and unmet need is essential to the development of successfully commercialized tests. Important considerations include sample type and collection, the timing of testing (asymptomatic, contact of a known case, or symptomatic), biosafety, the limit of detection and sensitivity, specificity, the turnaround time, form factor and workflow, internal controls, early verification and validation, and supply chain bottlenecks.

The Rapid Acceleration of Diagnostics (RADx®) Regulatory Core was established as part of the National Institutes of Health (NIH)-funded RADx US response to the COVID-19 pandemic. The RADx Regulatory Core is charged with supporting COVID-19 in vitro diagnostic manufacturers admitted into the RADx program with the goal of obtaining Emergency Use Authorization (EUA) and planning for full authorizations to increase COVID-19 testing throughput on the US market. This chapter outlines the EUA process and how it differs from full authorization and describes the inception and evolution of the RADx Regulatory Core, including collaborations made with the NIH, the US Food and Drug Administration, and industry sponsors to successfully bring new tests to the market.